Dr. Ir. Wilhelmus J. Geerts

PhD. University of Twente, The Netherlands (1992).
MSc. Electrical Engineering, University of Technology Eindhoven, The Netherlands (1987).

Dr. ir. Wilhelmus J. Geerts

Professor

Department of Physics
Texas State University
601 University Drive
San Marcos, TX 78739

Office:  Cell 512-801-4061
email: wjgeerts@txstate.edu

 

Research Interest

Dr. Geerts’ research focuses on the optical, electrical, mechanical, and magnetic characterization of thin films and multilayers. Topics of interest include:

  • Magnetic Field Assisted Additive Manufacturing: new materials and methods for application in novel Halbach cylinders in motors, generators, clutches, and permanent magnets.
  • Novel Magnetic Measurement Methods including dual beam modulated ellipsometry, triaxial Vibrating Sample Magnetometry, and automatic correction for field angle, field or temperature induced sample position shifts in biaxial VSMs
  • heterostructure devices on Ga2O3 for application in high power electronics.
  • Magneto-elastic and Magneto-plastic properties of thin films and novel magnetic composites for applications in motors, actuators, and artificial muscles.
  • Wide bandgap Organic Perovskite thin films deposited by solvent processing for application in under water and tandem solar cells.

Geerts studied under Lodder and Popma at the University of Twente the surface properties of thin Co-Cr layers with various surface sensitive techniques including STM, AFM, XPS, Auger and Magneto-Optical Kerr magnetometry. Using Shannon’s information theory he developed a model to estimate how surface artifacts such as oxidation-segregation scales, surface roughness, and demagnetizing effects, impact the maximum recording density in perpendicular magnetic recording media. In the early nineties he worked with Drs. Y. Suzuki and T. Katayama at ETL (Tsukuba, Japan) on the magneto-optical finite size effects in thin ferromagnetic films. Using a Jasco spectrometer the Kerr rotation of Fe and Caip o thin films was shown to oscillate as a function of the film thickness. During a 2nd postdoc at NHMFL in Florida under supervision of Prof. Pearton and Childress, he developed MOKE3, a probe to measure the magneto-optical properties at low temperatures (down to 2 Kelvin) and in high magnetic fields.  The probe allows one to measure the Kerr rotation and Kerr ellipticity in fields up to 20 tesla and still holds the world record as of today.

Refereed Journal and refereed conference papers:

  1. Nischal Khakurel, Drew Amyx, Yoichi Miyahara, Maggie Chen, Wilhelmus J. Geerts, “Slot-die coating of Formamidinium-Cesium mixed halide perovskites in ambient conditions with FAAc additive”, MRS Communications, February 17, 2024, https://doi.org/10.1557/s43579-024-00522-x (impact factor 1.66).
  2. Md Abdul Halim, Subrata Karmakar, Sourav Das, Wilhelmus J. Geerts, Ariful Haque, Gary W. Beall, “Crystallite Size-dependent Magnetic Moment in Hydrogen Bridged Manganese Tetracyanonickelate based Two-dimensional metal-Organic Frameworks”, J. Magn. Magn. Mat. 571, (2023) 170573 pp 1-11, (impact factor 2.92): https://www.sciencedirect.com/science/article/pii/S0304885323002226?via%3Dihub.
  3. Amanda de Oliveira Barros, Md Nayeem Kashem, Daniel Luna, Wilhelmus J. Geerts, Wei Li, James Yang, “Kinematic Modeling and Design of Untethered Soft Mobile Magnetic Robots with Multiple Support Sections”, Acta Mechanica 234 (2023) pp. 3519-3531 (impact factor 2.64), https://link.springer.com/article/10.1007/s00707-023-03572-9.
  4. Samuel W. Kimmel, Barry D. Koehne, Ben Gibson, Wilhelmus J. Geerts, Nikoleta Theodoropoulou, Christopher Rhodes, “Structure and Magnetism of Iron-Substituted Nickel Hydroxide Nanosheets”, Magnetochemistry 9, 25 (2023), https://www.mdpi.com/2312-7481/9/1/25. Graphical abstract posted on cover: https://www.mdpi.com/2312-7481/9/1 (impact factor 3.336).
  5. Mandesh Khadka, Oluwasola K. Arigbabowo, Jitendra Tate, Wilhelmus J. Geerts, “The Magnetic Anisotropy of Field-Assisted 3D printed Nylon Strontium Ferrite composites”, accepted for publication in AIP-Advances, January 8, 2024 (impact factor 1.697).
  6. Gabriela Espinosa-Rodriguez, Oluwasola Arigbabowo, Jonathan Alvarado, Jitendra Tate, Wilhelmus J. Geerts, “Wire Texture C-axis Distribution of Strontium Ferrite / PA-12 Extruded Filament”, accepted for publication in AIP Advances, December 26, 2023 (impact factor 1.697).
  7. Leo Rodriguez, Arjun Sapkota, Jonathan Alvarado, Jitendra Tate, Wilhelmus Geerts, “Computational Modelling of a Triaxial Vibrational Sample Magnetometer AIP Advances 14, 2, 025306, 2024, Computational modelling of a triaxial vibrating sample magnetometer | AIP Advances | AIP Publishing (impact factor 1.697).
  8. Arjun Sapkota, Leo Rodriguez, Binod D.C., Kolton Dieckow, Chandan Q Howlader, Wilhelmus J. Geerts, Jitendra Tate, “On the origin of systematic errors in VSM torque curves”, AIP Advances 14, 1, 015048, 2024, On the origin of systematic errors in VSM torque curves | AIP Advances | AIP Publishing (impact factor 1.697).
  9. Q. Howlader, W. Geerts, Y.M. Chen, “Selection of hole transport layer for Pb-Sn binary perovskite solar cells”, Proceedings of the SPIE 12659 (2023) 1265908, pp. 1-9, Organic, Hybrid, and Perovskite Photovoltaics XXIII, https://doi.org/10.1117/12.2678004 (impact factor 0.37).
  10. Oluwasola K. Arigbabowo, Jitendra Tate, Wilhelmus J. Geerts, “High Performance Thermoplastic Based Magnetic Composites”, SAMPE 2023 International Conference Proceedings, Seattle, WA, April 17-20, 2023. Society for the Advancement of Material and Process Engineering, North America, ISBN: 978-1-934551-43-1, pp 1713-1729.
  11. Tanjina N. Ahmed, Christopher Selsor, Jitendra S. Tate, Wilhelmus J. Geerts, “Magnetic Behavior and Chaining of Strontium Ferrite-Nylon Composite Above the Melting Temperature”, accepted for publication in AIP Advances, January 11 2023.
  12. Samuel R. Cantrell, Eric Welch, Luisa Scolfaro, Wilhelmus J. Geerts, “Opto electronic properties of carbon doped NiO”, J. Phys. and Chem. Solids, November 14 (2022), 111110, https://doi.org/10.1016/j.jpcs.2022.111110.
  13. Tanjina N. Ahmed, Camila Belduque, Maggie Y. Chen, Jitendra S. Tate, Wilhelmus J. Geerts, “Dynamic Viscosity of Strontium Ferrite-Nylon Composite Below the Melting Temperature, AIP Advances 12, 095223 (2022), https://doi.org/10.1063/5.0098972.
  14. C.Q. Howlader, B. Mishra, N. Khakurel, D.W. Amyx, W. Geerts. G. Gibson, M. Chen, “Fabricate anti-solvent free tin-lead based perovskite solar cells with MAAc additives”, SPIE conference proceedings vol. 12209, 1220905-1 1220905-6, (October 4 2022), https://www.spiedigitallibrary.org/proceedings/Download?urlId=10.1117%2F12.2634371&downloadType=proceedings%20article&isResultClick=True
  15. C.Q. Howlader, N. Khakurel, D.W. Amyx, W. Geerts, G. Gibson, M. Chen, Pin-Hole free MAPb0.75Sn0.25(I0.5Br0.5)3 films spin casted without anti-solvent by adding MAAc additive to Perovskite ink, Renewable Energy and Power Quality Journal 20, September 2022, pp. X-1-5, ISSN 2172-038 X, https://www.icrepq.com/icrepq22/284-22-howlader.pdf.
  16. Amanda de Oliveira Barros, Md Nayeem Hasan Kashem, Danny Luna, Wilhelmus J. Geerts, Wei Li, James Yang, “Magnetic Properties of PDMS Embedded with Strontium Ferrite Particles Cured Under Different Magnetic Field Conditions”, AIP Advances 12, 035121 (2022), https://aip.scitation.org/doi/10.1063/9.0000338.
  17. Md Dalim Mia, Brian Samuels, Ahad Talukder, Pablo D. Borges, Luisa Scolfaro, Wilhelmus J. Geerts, Ravi Droopad, “Theoretical and experimental study of (Ga1-xFex)2O3 ternary alloys”, J. Cryst. Growth 575 (2021) 126353, pp. 1-11 (impact factor 1.797).
  18. Lauren Henderson, Sam Zamora, Tanjina N. Ahmed, Camila Belduque, Jitendra Tate, Maggie Yihong Chen, Wilhelmus J. Geerts, “Altering Magnetic properties of Iron Filament PLA using Magnetic Field Assisted Additive Manufacturing (MFAAM)”, J. Magn. Magn. Mat. 38 (2021) 168320 (impact score 3.05).
  19. Tanjina Nasreen Ahmed, Maria Camila Belduque, Binod D.C., Jitendra Tate, Wilhelmus J. Geerts, “Time dependence of magnetic moment of strontium-ferrite powder measured with a biaxial vibrating sample magnetometer (VSM)”, AIP Advances 11, 015048 (2021), https://doi.org/10.1063/9.0000216.
  20. Camila Belduque, Tanjina Ahmed, Wilhelmus Geerts, Subash Panta, Harrison Thramann, Liam Omer, Jitendra Tate, “Mechanical Properties of re-extruded SrFe12O19(OP-71)/PA12 Filaments via twin-screw extrusion for fused filament fabrication”, CAMX-2021 conference proceedings ISBN Number: 978-1-934551-39-40-0, October 2021, Dallas.
  21. . Camila Belduque, Ryan Robinson, Adrian Medina, Tanjina Ahmed, Rijul Kala,
    Wilhelmus Geerts, and Jitendra Tate, “Magnetic and Mechanical characterization of Additive Manufactured Strontium Ferrite/Polyamide 12 Composites using Twin-Screw and Single-Screw Extrusion”, SAMPE 2021 conference proceedings, ISBN Number: 978-1-934551-39-4, Long Beach, CA, May 24-27, 2021
  22. James Shook, Pablo D. Borges, Wilhelmus J. Geerts, Luisa M. Scolfaro, “Evaluation of Ni doping for promoting favorable electronic structures in CuCrO2 and AgCrO2 from a first-principles perspective”, Ceramics International 46 (2020) 26777-26783 (impact factor 3.64).
  23. Fidele J. Twagirayezu, Md. Abdul Ahad Talukder, Wilhelmus J. Geerts, “Magnetic Properties of RF sputtered NiO and Ni0.8Fe0.2O1-d samples grown on SiO2/Si substrates”, Materials Research Innovations 24 (2020), pp. 44-51.
  24. Shankar Acharya, Brian Collier, Wilhelmus Geerts, “Dual Beam Modulated Magneto-Optical Measurement Setup”, Rev. Sci. Instr. 90 (2019) 123001.
  25. James N. Talbert, Samuel R. Cantrell, Md. Abdul Ahad Talukder, Luisa M. Scolfaro, Wilhelmus J. Geerts, “, “Electrical Characterization of Silicon – Nickel Iron Oxide Heterojunctions”, MRS Advances 4 (2019) 2241-2248, DOI: 10.1557/adv.2019.32
  26. Binod D.C., Andres Oliva, Anival Ayala, Shankar Acharya, Fidele Twagirayezu, James Nick Talbert, Luisa M. Scolfaro, Wilhelmus J. Geerts, “Magnetic Properties of reactive co-sputtered NiFe-oxide samples”, IEEE Trans. on Magn. 55 (2019) 2900205-1-6, DOI: 10.1109/TMAG.2018.2866788.
  27. John Petersen, Luisa M. Scolfaro, Pablo D. Borges, Wilhelmus J. Geerts, “Symmetry consideration on band filling and first optical transition in NiO”, Eur. Phys. J. B (2019): 92:232, https://doi.org/10.1140/epjb/e2019-100363-5.
  28. James Shook, Pablo D. Borges, Luisa M. Scolfaro, Wilhelmus J. Geerts, “Effects of vacancies and p-doping on the optoelectronic properties of Cu- and Ag-based transparent conducting oxides”, J. Appl. Phys. 126 (2019) 075702.
  29. James Shook, Luisa M. Scolfaro, Pablo D. Borges, Wilhelmus J. Geerts, “Structural stability and electronic properties of XTO2 (X=Cu, Ag; T=Al, Cr): An ab initio study including X vacancies and Mg doping, Solid State Physics 88 (2019), pp. 48-56.
  30. Md. Abdul Ahad Talukder, Wilhelmus J. Geerts, “Jones matrix description of Fabry-Perot interference in a single axis photoelastic modulator and the consequences for the magneto-optical measurement method”, AIP Advances 7, 085320 (2017), https://doi.org/10.1063/1.4999517.
  31. John E. Petersen, Fidele Twagirayezu, Luisa M. Scolfaro, Pablo D. Borges, Wilhelmus J. Geerts, “Electronics and Optical properties of antiferromagnetic Iron doped NiO – A first principles study”, AIP Advances, vol. 7, 05571 1-5, 2017; doi: 10.1063/1.4975493.
  32. Md. Abdul Ahad Talukder, Wilhelmus J. Geerts, “Tilt angle dependence of the modulated interference effect in Photo-elastic Modulators”, AIP Advances, vol. 7, 056719 1-4, 2017; doi: 10.1063/1.4975999.
  33. John Petersen, Fidele Twagirayezu, Pablo D. Borges, Luisa Scolfaro, Wilhelmus Geerts, “Ab initio study of oxygen vacancy effects on electronics and optical properties of NiO”, MRS Advances 1, 37 (2016), pp. 2617-2622.
  34. Md. Abdul Ahad Talukder, Yubo Cui, Maclyn Compton, Luisa Scolfaro, Stefan Zollner, FTIR Ellipsometry study on RF sputtered Permalloy-oxide Thin Films, MRS Advances 1, 49 (2016), pp. 3361-3366.
  35. Jonathan Tamir, Dan Tamir, Wilhelmus Geerts, Sholmi Dolev, Compressive Scanning of an Object Signature, Natural Computing 14, issue 3 (2015), 457-467, DOI 10.1007/s11047014-9460-7.
  36.  Wilhelmus J. Geerts, Nelson Simpson, Maclyn S. Compton, Alan Woodall, “Indium Tin Oxide thin films deposited at low temperature using Dual Ion Beam Sputtering”, Materials Research Society Symposium Proceedings 1699 (2014), mrss14-1699-ll05-28 (6 pages), doi:10.1557/opl.2014.523.
  37. Maclyn Compton, Nelson Simpson, Elizabeth Leblanc, Michael A. Robinson, Wilhelmus J. Geerts, “Electrical and Optical Properties of Permalloy Oxide grown by dual ion beam sputtering”, Materials Research Society Symposium Proceedings 1708 (2014), mrss 14-1708VV08-01 (6 pages), doi:10.1557/opl.2014.621.
  38. Dan Tamir, Natan Shaked, Wilhelmus Geerts, Shlomi Dolev, “Parallel Decomposition of Combinatorial Optimization Problems Using Electro-Optical Vector by Matrix Multiplication Architecture”, The Journal of Supercomputing 25 (2012 in print), pp. 633-655 (impact factor 0.687).
  39. R. K. Pandey P. Padmini, P. Kale, J. Dou, C. Lohn, R. Schad, R. Wilkins and W. Geerts, Multifunctional Nature of modified iron titanates and their potential applications, Advances and Applications in Electroceramics, K.M. Nair, Quanxi Jia, Shashank Priya, Ceramic Transactions, 226, Wiley (2011) pp. 61-75.
  40. D. E. Tamir, N. T. Shaked, W. J. Geerts, and S. Dolev, “Compressive Sensing of ObjectSignature,” Lecture Notes in Computer Science, 2011, Volume 6748, Proceedings of the 3nd International Workshop on Optical Super Computing, Bertinoro, Italy, November 2010.
  41. Martin J. Sablik, Wilhelmus J. Geerts, Kyle Smith, Amanda Gregory, Clayton Moore, Daniel Palmer, Anup Bandyopadhyay, Fernando J. G. Landgraf, Marcos F. de Campos, “Modelling of Plastic deformation effects in Ferromagnetic Thin Films”, IEEE Trans. on Magn. 46 (2010) pp. 491 (impact factor: 1.13).
  42. R.K Pandey, P. Padmini, R. Schad, J. Dou, H. Stern, R. Wilkins, R. Dwivedi, W.J. Geerts, and C.O’Brien, “Novel Magnetic-Semiconductors in Modified FeTiO3 for Radhard Electronics”, J. Electroceramics 22 (2009) pp. 334–341 (impact factor 0.99).
  43.  Dan E. Tamir, Natan T. Shaked, Wilhelmus J. Geerts, Shlomi Dolev, “Combinatorial Optimization Using Electro-Optical Vector by Matrix Multiplication Architecture”, Lecture Notes in Computer Science 5882 (2009) 130-143 (impact factor 0.52).
  44. Christopher Lohn, Wilhelmus J. Geerts, Chris B. O’Brien, J. Dou, P. Padmini, K. Pandey, R. Schad, “IV and CV Characteristics of multifunctional Ilmenite-Hematite 0.67FeTiO30.33Fe2O3”, Functionalized Nanoscale Materials, Devices and Systems, NATO Science for Peace and Security Series B: Physics and Biophysics, Volume . ISBN 978-1-4020-8902-2. Springer Netherlands, 2008, p. 419-424.
  45. R. K. Pandey, H Stern, W.J. Geerts, P Padmini, P. Kale, J. Dou, R. Schad, Room Temperature Magnetic-Semiconductors in Modified Iron Titanates: Their Properties and Potential Microelectronic Devices, Advances in Science and Technology 54 (2008) pp 216222.
  46. R.K. Pandey, P. Padmini, L.F. Deravi, N.N. Patil, P. Kale, J. Zhong, J. Dou, L. Navarrete, R. Schad, M. Shamsuzzoha, C. O.Brien, W.J. Geerts, “Magnetic-Semiconductors in Fe-TiOxide Series and their Potential Applications”, proceedings of the 8th International Conference on Solid-State and IC Technology, October 23-24 2006, Shanghai, China.
  47. C.B. Craus, T. Onoue, K. Ramstock, W.J.M.A. Geerts, M.H. Siekman, L. Abelmann, and J.C. Lodder, A read and write element for magnetic probe recording, J. Phys. D: Appl. Phys. 38 (2005) 363-370.
  48. Gabriel H. Monreal, Michael Blanda, Wilhelmus Geerts, Heather Galloway, Gregory F. Spencer, A conformationally-immobile, partially-functionalized calixarene as a negative electron beam resist, J. Vac. Sc. Techn. B 23 (2005) pp. 1998 (impact factor 1.63).
  49. Andrew P. Schuetze, Wayne Lewis, Chris Brown, Wilhelmus J. Geerts, “A Lab Class on the Four-Point Probe Technique”, Am. J. Phys 72 (2004) pp. 149 (impact factor 0.72).
  50. Frances Hellman, Wim Geerts, Brian Donehew, “Magneto-optic Measurements of Amorphous Gd-Si Alloys”, Phys. Rev. B 67 (2003) 12406 (impact factor 3.327)
  51. Claude Garrett, Patrick Holland, Wilhelmus J. Geerts, Dustin Ragan, Archana Dubey, Steve Rios, Anup K. Bandyopadhyay, “Thickness Dependence of the Magnetic Hysteresis of NiFe-31% Films as a Function of an Applied Isotropic In-plane Stress”, J. Appl. Phys 93, pp.  8624-8627 (2003) (impact factor 2.28).
  52. Patrick Holland, Mary Kempton, Dustin Ragan, Steve Rios, Anup K. Bandyopadhyay, Archana Dubey, Wilhelmus J. Geerts, “Magnetic Hysteresis Measurements of Thin Films of NiFe-31% under Isotropic Stress”, J. Magn. Magn. Mat. 250 (2002) L1-L5 (impact factor 1.05).
  53. Wilhelmus Geerts, Brian Donehew, Vaughan Williams, Thomas Schmiedel, “A Set-up for Measuring Magneto-optical Kerr Hysteresis Curves at High Fields and Low Temperature”, Rev. Sci. Instrum 73 (2002) 2086 (impact factor 1.44).
  54. Ena S. Bichsel, Brenda Wilson, Wilhelmus J. Geerts, “Recorded Bit Pattern Imaging of Floppy Disks and Phone-cards with Toner-Fluid”, The Physics Teacher 40 (2002) 150.
  55. J.R. Childress, J.A. Caballero, W.J. Geerts, F. Petroff, P. Galtier, Y. Suzuki, J.-U. Thiele, and D. Weller, “Low-temperature growth of NiMnSb Heusler alloy thin films”, in Magnetic Ultrathin Films, multilayers, and surfaces, Mat. Res. Soc. Symp. Proc. 475 (1997) 15.
  56. J.A. Caballero, W.J. Geerts, F. Pettroff, F. Thiele, “Magnetic and magneto-optical properties of NiMnSb thin films”, J. Magn. Magn. Mat. 177-181 (1998) 1229-1230.
  57. J. Hong, J.A. Caballero, W. Geerts, J.R. Childress, S.J. Pearton, “Dry and Wet Etch Processes for NiMnSb Heusler Alloy Thin Films”, J. Electrochem. Soc. 144 (1997) 3602.
  58. J.A. Caballero, W.J. Geerts, and J.R. Childress, F. Petroff and P. Galtier, J.-U. Thiele and D. Weller, “Structure and Magneto-Optical Properties of Sputter-Deposited NiMnSb Thin Films”, Appl. Phys. Lett. 71 (1997) 2382.
  59. Y. Suzuki, T. Katayama, W. Geerts, P. Grunberg, K. Takanashi, R. Schreiber, P. Bruno, and S. Yuasa, “Magneto-Optical effects of ultrathin ferro-, antiferro and non-magnetic films”, in Magnetic ultrathin films, multilayers and surfaces, Mat. Res. Soc. Symp. Proc. 475 (1997) 227.
  60. W. Geerts, J.D. MacKenzie, C.R. Abernathy, S.J. Pearton, and T. Schmiedel, “Temperature dependence of the electrical transport of carbon doped GaN”, in Compound Semiconductor Electronics and Photonics, Mat. Res. Soc. Symp. 421 (1996) 425.
  61. J. Hack, M.H. Ludwig, W. Geerts, R.E. Hummel, “Ferromagnetic Properties of Spark Processed Photoluminescing Silicon”, in Advances in microcrystalline and nanocrystalline semiconductors, Mat. Res. Soc. Symp. Proc. 452 (1996) 147.
  62. W. Geerts, T. Katayama, Y. Suzuki, J. Childress, “Wavelength dependence of the magnetooptical properties of the interfaces of a Au sandwiched (001) Fe film”, J. Vac. Sci. Techn. B 14 (1996) 3176.
  63. T. Katayama, W. Geerts, Y. Suzuki, D. Fujitani, N. Okuzawa, “Oscillation of magnetooptical Kerr effect in Co ultra-thin films”, J. Magn. Magn. Mat. 156 (1996) 171.
  64. N. Okuzawa, T. Katyama, D. Fujitani, W. Geerts, and Y. Suzuki, “Magneto-Optical Kerr effect in different surfaces of epitaxially grown Co Films”, J. Magn. Soc. Jpn. 20 (1996) 193.
  65. W. Geerts, J.D. MacKenzie, C.R. Abernathy, S.J. Pearton, and T. Schmiedel, “Electrical transport in p-GaN, n-InN, and n-InGaN”, Solid State Electronics 39 (1996) 1289-1294.
  66. N. Bardou, B. Bartenlian, F. Rousseaux, D. Decanini, F. Carcenac, E. Cambril, M.F. Ravet, C. Chappert, P. Veillet, P. Beauvillain, R. Megy, W. Geerts, J. Ferre, “Elaboration and magneto-optical study of submicron magnetic structures in Au/Co/Au ultrathin films”, J. Magn. Magn. Mat. 156 (1996) 139.
  67. T. Katayama, Y. Suzuki, W. Geerts, “Magneto-Optical transition due to a formation of quantum well states in magnetic ultra-thin films and multilayers (invited)”, J. Magn. Magn. Mat. 156 (1996) 158.
  68. Y. Suzuki, W. Geerts, T. Katayama, “The Magneto-Optical quantum size effect of ultra-thin epitaxial Fe films”, Optoelectronics-Devices and Technologies 10 (1995) 269.
  69. W. Geerts, T. Katayama, and Y. Suzuki, “On the oscillation of the magneto-optical properties of ultrathin epitaxial Fe films (invited)”, J. Magn. Soc. Jpn. 19, S1 (1995) 309.
  70. T. Katayama, D. Fujitani, W. Geerts, N. Okusawa, Y. Suzuki, C.-G. Lee, H. Takeda, H. Kataoka, K. Fukamichi, and Y. Shimada, “Magneto-Optical Kerr Rotation Spectra in sputtered granular Co-Au alloy films”, J. Magn. Soc. Jpn. 19, S1 (1995) 243.
  71. Y. Suzuki, T. Katayama, W. Geerts, P. Bruno, H. Sawada, “Magneto-Optical quantum size effect in bcc-Fe (001) and (110) ultrathin films (invited)”, Mat. Res. Soc. Symp. Proc. 382 (1995) 237.
  72. T. Katayama, Y. Suzuki, W. Geerts, “A new Magneto-Optical Effect due to Quantum Well States in Metallic Ultrathin films”, ETL reports  7 (1995) 63.
  73. W. Geerts, Y. Suzuki, T. Katayama, K. Tanaka, K. Ando and S. Yoshida, “Thickness dependent oscillation of the magneto-optical properties of Au-sandwiched (001) Fe films”, Phys. Rev. B 50 (1994) 12581.
  74. T. Katayama, Y. Suzuki, M. Hayashi, and W. Geerts, “Change of Magneto-Optical Kerr rotation due to interlayer thickness in magnetically coupled films with noble-metal wedge”, J. Appl. Phys. 75 (1994) 6360.
  75. W. Geerts, C. Lodder, Th. Popma, “Biaxial Kerr Magnetometry in oblique field for the study of thin films with a perpendicular anisotropy”, J. Magn. Magn. Mat. 137 (1994) 224.
  76. M. Hayashi, T. Katayama, Y. Suzuki, M. Taninaka, A. Thiaville, W. Geerts, “MagnetoOptical Kerr rotation spectra in Fe ultrathin film on noble metals”, J. Magn. Magn. Mat. 126 (1993) 547-549.
  77. W.J.M.A. Geerts, J.C. Lodder, Th.J.A. Popma, “A combined optical and magneto-optical measurement system”, Rev. Sc. Instrum. 64 (1992) 1805.
  78. W.J.M.A. Geerts, J.C. Lodder, Th.J.A. Popma, “Surface properties and stray fields of RFsputtered Co-Cr films”, J. Magn. Magn. Mat. 104-107 (1992) 971-972.
  79. Wim Geerts, “Magnetization Distribution at the surface of Co-Cr films: Magneto-Optical, Chemical and Structural characterization”, ISBN NR 90-9004803, Enschede, The Netherlands, 1992.
  80. J. Simsova, V. Kambersky, R. Gemperle, J.C. Lodder, W.J.M.A. Geerts, B. Otten, P. ten Berge, “Domainstructure of Co-Cr films”, J. Magn. Magn. Mat. 101 (1991) 196-198.
  81. T. Masuda, W.J.M.A. Geerts, J.C. Lodder, “Surface chemical state of sputtered Co-Cr films”, J. Magn. Magn. Mat. 101 (1991) 123.
  82. W.J.M.A. Geerts, J.G.Th. te Lintelo, J.C. Lodder, Th.J.A. Popma, “Anomalous Hc in Co-Cr films, IEEE Trans. Magn. 26 (1990) 36-38.

Current Support:

  1. PI on “MRI: Development of Full Vector Vibrating Sample Magnetometry for Materials Research and Education”, (Wim Geerts, Jitendra Tate, Maggie Chen, Ravi Droopad, Chris Rhodes), 09/01/2022 – 08/31/2024, NSF-MRI ($121,364).
  2. PI on “Study of Migration and Diffusion in Hybrid Halide Perovskites Solar Cell Devices: effect on Stability and Efficiency”, Research Enhancement grant TxState university (together with Luisa Scolfaro), January 2024, May 2025.