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MA: Fachverband Magnetismus
MA 9: Cooperative Phenomena: Spin Structures and Magnetic Phase Transitions
MA 9.3: Talk
Monday, March 27, 2023, 15:30–15:45, HSZ 401
Subsequent Mott transitions and magnetic ground state in NiS2 — •Jonas A. Krieger1, Fabio Orlandi2, Mikel I. Iñurrieta3, Iñigo Robredo3, Zaher Salman4, Niels B. M. Schröter1, Maia Garcia-Vergniory3, Stuart S. P. Parkin1, and Leslie Schoop5 — 1Max Planck Institute of Microstructure Physics, Halle, Germany — 2Rutherford Appleton Laboratory, Didcot, UK — 3Donostia International Physics Center, San Sebastián, Spain — 4Paul Scherrer Institute, Villigen, Switzerland — 5Princeton University, Princeton, USA
We present muon spin spectroscopy (µSR) measurements on the antiferromagnetic Mott insulator NiS2. This compound features two subsequent magnetic phase transitions around 38.9K and 29K associated with the opening of a Mott gap. From the zero field and rotation dependence of transverse field µSR spectra we confirm the magnetic space group 205.33 in the 38.9K to 29K phase, determined from neutron diffraction [1]. We refine the muon stopping sites by using ab-initio density functional theory (DFT) and show that the resulting 8c and 24d muon sites can fully explain the observed µSR precession frequencies. A disproportionate temperature evolution of the two frequencies associated with these sites points to the presence of a strong temperature dependence in the muon hyperfine coupling strength due to concomitant changes in the electronic structure. We then use the number of µSR frequencies in combination with complementary neutron diffraction results to identify the magnetic ground state.
[1] S. Yano, et al., Phys. Rev. B 93, 024409 (2016)