SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Magnetic Instrumentation and Characterization
MA 48.7: Vortrag
Freitag, 31. März 2023, 11:15–11:30, HSZ 401
Measuring Antiferromagnets at Room Temperature in a Magnetically Shielded Environment — •Michael Paulsen1, Silvia Knappe-Grüneberg1, Jens Voigt1, Allard Schnabel1, Rainer Körber1, Michael Fechner2, and Dennis Meier3 — 1Physikalisch-Technische Bundesanstalt, Berlin, Germany — 2Max Planck Institute for the Structure and Dynamics of Matter, CFEL, Hamburg, Germany — 3NTNU Norwegian University of Science and Technology, Trondheim, Norway
Antiferromagnetic materials possess zero net dipole magnetization. However, higher-order magnetizations, such as quadrupolar magnetic field contributions, have been predicted for non-centrosymmetric antiferromagnets. Classical low-temperature measurements on Cr2O3 [1] indeed indicated an external quadrupole field at 4.2 K [2, 3], but the validity of the results was put into question due to the limited sensitivity of the applied experiment. Here, we present magnetization measurements gained at room temperature in an ultra-low magnetic field environment (< 1 nT). A multi-channel setup with Superconducting Quantum Interference Devices (SQUIDs) and Optically Pumped Magnetometers (OPMs) are used as magnetic field detectors. The results corroborate the emergence of a quadrupolar far-field in Cr2O3, providing new opportunities for the characterization of antiferromagnets and materials with ultra-small remanent magnetization in general.
[1] I. Dzyaloshinskii, Sol. Stat. Comm. 82:7, 579-580, 1992.
[2] D. N. Astrov and N. B. Ermakov, JETP, 59:4, 274-277, 1994.
[3] D. N. Astrov et al, JETP Letters, 63:9, 745-751, 1996.