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TT: Fachverband Tiefe Temperaturen

TT 50: Quantum-Critical Phenomena I

TT 50.2: Vortrag

Mittwoch, 14. März 2018, 09:45–10:00, H 3005

Close proximity of FeSe to a magnetic quantum critical point as revealed by high-resolution µSR measurements — •Vadim Grinenko^1,2, Rajib Sarkar¹, Philipp Materne¹, Sirko Kamusella¹, Aichi Yamashita³, Yoshihiko Takano³, Yue Sun⁴, Tsuyoshi Tamegai⁴, Dmitriy Efremov², Stefan-Ludwig Drechsler², Jean-Christophe Orain⁵, Tatsuo Goko⁵, Robert Scheuermann⁵, Hubertus Luetkens⁵, and Hans-Henning Klauss¹ — ¹Institute for Solid State and Material Physics, TU Dresden, 01069 Dresden, Germany — ²IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany — ³National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, 305-0047 JAPAN, Japan — ⁴Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan — ⁵Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland

We investigated FeSe single crystals using high-field (up to 9.5 T) muon spin rotation (µSR) measurements. We observed that the muon spin depolarization rate follows a critical behavior Λ² ∝ T^−3/4 in the temperature range T_s T 10 K. The scaling between Λ² and the NMR 1/T₁T suggests that Λ ∝ 1/T₂ spin-spin relaxation rate. The observed non-Fermi liquid behavior with a cutoff at T^* ∼ 10 K indicates that FeSe is close to a magnetic quantum critical point. The µSR Knight shift and the bulk susceptibility linearly scale at high temperatures but deviate from this behavior below T^* where the Knight shift exhibits a kink. Our analysis shows a reduction of the density of states crossing the region near T^* maybe related to a Lifshitz transition.