[PC8] Nickelates, Iron-based

4:15 PM - 4:30 PM JST(7:15 AM - 7:30 AM UTC)

[PC8-05] Magnetic Order in S-substituted FeSe_1-xS_x Thin Films Grown on LaAlO₃ Substrates

*Kazuki Miwa¹, Yuma Kawai¹, Fuyuki Nabeshima², Andreas Suter³, Zaher Salman³, Thomas Prokscha³, Atsutaka Maeda², Tadashi Adachi¹ (1. Sophia Univ. (Japan), 2. University of Tokyo (Japan), 3. PSI Center for Neutron and Muon Sciences (Switzerland))

Keywords:

Iron-chalcogenide superconductor,FeSe1-xSx,Thin film,Low-energy muon

Iron-chalcogenide superconductor FeSe does not exhibit a magnetic order but a nematic order at ambient pressure, whereas a magnetic order is induced by hydrostatic pressure [1]. In S-substituted FeSe_1-xS_x in which the nematic transition temperature decreases monotonically with increasing x, it has been suggested that spin fluctuations develop around x = 0.1 [2]. In our former muon spin relaxation (muSR) measurements on FeSe_1-xS_x thin films, it was observed that a short-range magnetic order was formed at low temperatures for x = 0.3 and 0.4 [3]. Therefore, to investigate spin fluctuations in the low S-concentration regime where the nematic order is formed, we fabricated FeSe_1-xS_x thin films by pulsed laser deposition and performed muSR measurements using low-energy muons at PSI, Switzerland. For x = 0.1, muon spin precession was observed at low temperatures, indicating the formation of a long-range magnetic order. This is likely because enhanced spin fluctuations are stabilized into a magnetic order by lattice strain originating from the substrate. Figure1 shows the S-concentration dependence of the magnetic transition temperature T_m in FeSe_1-xS_x thin films. For x = 0, a magnetic transition occurs at 80 K, and Tm decreases with increasing x. However, T_m increases above x = 0.2. This suggests a change in the magnetic state around x = 0.2.

References
1) M. Bendele et al. Phys. Rev. Lett. Vol.104, p087003, 2010
2) P. Wiecki et al. Phys. Rev. B Vol.98, p020507(R), 2018
3) F. Nabeshima et al. Phys. Rev. B Vol.103, p184504, 2021
4) F. Nabeshima et al. J. Phys. Soc. Jpn. Vol.87, p073704, 2018