Quantum spin Hall state at Room temperature*

Search for macroscopic quantum phenomena at room temperature is a major pursuit in physics. There has been only a single definitive report of such a phenomenon, namely the room-temperature integer quantum Hall effect at ultra-high magnetic fields [1]. In this poster, I will present our discovery of a zero-magnetic field, room-temperature quantum phenomena- quantum spin Hall state featuring a bulk energy gap and a gapless, in-gap edge state protected by the time-reversal symmetry [2].  Our material platform is Bi4Br4, which has a large energy gap, facilitating the high-temperature robustness of the quantum spin Hall state.

[1] Science 315, 1379 (2007).

[2] Nature Materials 21, 1111 (2022).