Quantum Detection

Prof. Dr. Heidemarie Schmidt is Professor for Solid State Physics and Quantum Detection at the Institute of Solid State Physics and and Head of the Research Department Quantum Detection at the Leibniz-IPHT, Jena, since 2017.

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.

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 as an electrostatic carrier in bioreactors, in implants, and in impedance biochips for cell counting [8].

[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).

link to the Schmidt research group at Leibniz-IPHTExternal link