137 136 Principal Scientist Profiles Heidemarie Schmidt Heidemarie Schmidt Principal Scientist Profiles PROFESSOR FOR SOLID STATE PHYSICS/QUANTUM DETECTION, IFK Prof. Dr. Heidemarie Schmidt received the “NanoFuturPrize” from BMBF in 2002 (1.7 Mio. Euro) and led the Young Scientist Group “Nano-Spintronics” at Uni Leipzig (2003-2007), HZDR (2007-2011), and TU Chemnitz (2011-2016). She was awarded a Heisenberg Fellowship from DFG (2012-2017), won an ATTRACT grant (2.1 Mio. Euro) from Fraunhofer-Gesellschaft, and since 2016 she is leading the ATTRACT group BFO4ICT at Fraunhofer ENAS Chemnitz. Since 2017 she is Professor (W3) for Solid State Physics and Quantum Detection at Friedrich Schiller University Jena and Head of the Research Department Quantum Detection at the Leibniz-IPHT, Jena. HEIDEMARIE SCHMIDT RESEARCH AREAS • Detectors for application in the life sciences and medical technology: impedance biochips • Cryogenic single photon detectors for applications in quantum optics, safety, and security • High-sensitivity, robust detectors and detector systems for applications in life science, medical technology, and environmental monitoring: IR sensors • AI hardware with analog and digital functionality for application in neuromorphic computing, sensor-near data analysis, and trusted electronics: analog, electroforming-free memristors and digital, electroforming-free memristors • Light-matter interaction in external fields: magnetooptics and electrooptics • Bound magnetic polaron formation in transparent oxide thin films: magnetotransport TEACHING FIELDS • Lectures on solid state optics in external fields I and II RESEARCH METHODS • Optical properties: IR spectrometer and UV-ViS spectral ellipsometer measurements • Magnetooptical properties: vector magnetooptical generalized ellipsometry (VMOGE) measurements and modelling • Transport properties: magnetoresistance measurements and modelling, Impedance measurements and modelling, current-voltage measurements and modelling • Thermoelectric properties: Seebeck coefficient measurements, thermal conductivity measurements • Scanning probe microscopy: Kelvin Force Probe Microscopy (KPFM), Photo Induced Force Microscopy (PiFM) RECENT RESEARCH RESULTS Magnetic oxide thin films with bound magnetic polarons (BMP) for transparent spintronics: We have fabricated magnetic, n-type conducting ZnO thin films and controlled the formation of BMP with huge collective spins by means of a structured metallization of the ZnO surface. The transport properties [DE102013209278B4] depend on concentration and species of magnetic ions and intrinsic defects [1]. Increased static dielectric constant [2] has been shown for magnetic ZnO thin films with BMP. Multilayer structures in magnetic thin films for magnetooptics: We have set-up a vector magnetooptical generalized ellipsometer (VMOGE) with an octupole magnet [3] and examined the magnetooptical response of multilayer structures with magnetic thin films. We have developed the 4×4 Mueller matrix method to extract the magnetooptical dielectric constant from the magnetic thin films. For magnetic metals (Fe, Co, Ni, Ni20Fe80 [4], Ni80Fe20, Co90Fe10, Co40Fe40B20) the extracted magnetooptical constants can be related with the results of spin DFT calculations. AI hardware for Neuromorphic computing, Sensor-near data analysis, and Trusted Electronics: Multiferroic thin film materials, e.g. BiFeO3 [5] and YMnO3 [6], with top electrode and bottom electrode are well-known as memristors, where the resistance state can by reconfigured into high resistance state (HRS) and low resistance state (LRS) by applying an appropriate voltage bias to or pushing an appropriate current through the memristor. We have analyzed the physical mechanism underlying the non-volatile resistive switching in BiFeO3 and YMnO3 memristors and have developed them into a novel AI hardware element [US9520445B2, DE102012104425B4, DE102014105639B3, US9583704B2, DE102016205860B4, US10,388,370B2, CN000109074842B, DE 10 2019 203 288, DE 10 2018 125 270.6, DE102018112605A1]. Charged silicon for use as electrostatic carriers and impedance biochips in biotechnology:Surface-near electrostatic forces above charged silicon have been measured using Kelvin Probe Force Microscopy (KPFM) and modelled using a model developed for the interpretation of KPFM data recorded on doped semiconductors [7]. Doped silicon is potentially useful [US201402911143A1, DE102018107810A1, DE 102020200470.6] as an electrostatic carrier [19] in bioreactors, in implants, and in impedance biochips for cell counting [8]. BOUND MAGNETIC POLARONS IN N-TYPE CONDUCTING, MAGNETIC, OXIDE THIN FILMS Bound magnetic polarons (BMP) strongly influence transport, magnetization, and magnetooptical properties in magnetic semiconductors within the confined volume of BMPs formation. The radius of BMP is directly proportional to the static dielectric constant. If BMPs are coalescing, strong effect of BMPs can be expected on the transport, magnetization, and magnetooptical properties of magnetic semiconductors, even at room temperature. We have measured and modelled room temperature impedance of metal/(ZnO or ZnMnO or ZnCoO)/insulator/semiconductor (MSIS) capacitive structure and modelled the static dielectric constant of ZnO and of ZnMnO and ZnCoO. We have confirmed the dielectric constant of ZnO in the range from 8.64 to 9.97. We consider the observed increase of static dielectric constant in ZnMnO and in ZnCoO with decreasing fraction of Mn and Co, respectively, as the key result of our work [Vegesna et al., Sci. Rep. 10, 6698 (2020)]. [1] Kaspar et al., IEEE Elect. Dev. Lett. 34, 12711273 (2013). [2] Vegesna et al., Sci. Rep. 10, 6698 (2020). [3] Mok et al., Rev. Sci. Instrum. 82, 033112 (2011). [4] Patra et al. J. Phys. D: Appl. Phys. 52, 485002 (2019). [5] Shuai et al., J. Appl. Phys. 109, 124117 (2011). [6] V. R. Rayapati et al., Nanotechnology 31, 31LT01 (2020). [7] Baumgart et al., Phys. Rev. B 80, 085305 (2009). [8] Kiani et al., Biosensors 10, 82 (2020). Contact: Phone: + 49 3641 206-116 Email: heidemarie.schmidt@uni-jena.de
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