Dresden 2026 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 95: Fe-based Superconductors
TT 95.3: Vortrag
Freitag, 13. März 2026, 10:00–10:15, HSZ/0103
Magnetic-field-induced Sarma state in atomically thin superconducting FeSe films — •Wantong Huang1,2, Yuguo Yin1, Haicheng Lin1, Wei Chen1, Yaowu Liu1, Lichen Ji1, Zichun Zhang1, Xinyu Zhou1, Xusheng Wang1, Yong Xu1, Lianyi He1, Xi Chen1, Qi-Kun Xue1, and Shuai-Hua Ji1 — 1State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China — 2Physikalisches Institut (PHI), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Many-body ground states of imbalanced Fermi gas have long been studied both theoretically and experimentally due to their fundamental significance in condensed matter physics, cold atom physics and nuclear physics. Among the predicted exotic phases, the Sarma state, a gapless spin-polarized superfluid, has remained experimentally elusive. Here, we report direct evidence for the Sarma state in atomically thin FeSe films using a dilution-refrigerator scanning tunneling microscope under high magnetic fields. In the bilayer and trilayer FeSe films, we observe the hallmark signature of the Sarma state: the inner Zeeman splitting coherence peaks cross the Fermi level under high in-plane magnetic fields. The angle dependent critical field exhibits a two-fold symmetry arisng from the anisotropic in-plane g-factor. Moreover, our two-band model shows that the magnetic field induced Sarma phase emerges via a first-order transition at zero temperature, which evolves into a smooth crossover at finite temperature. These findings pave the way to explore the unusual physical properties and potential applications of the spin-polarized Sarma superfluid state.
Keywords: Sarma state; scanning tunneling microscopy; In-plane field; Anisotropic g factor; dilution-refrigerator