Spontaneous Quantum Hall Effect in an Atomic Spinor Bose-Fermi Mixture

Abstract

We study a mixture of spin-1 bosonic and spin-1/2 fermionic cold atoms, e.g., 87 Rb and 6 Li, confined in a triangular optical lattice. With fermions at 3/4 filling, Fermi surface nesting leads to spontaneous formation of various spin textures of bosons in the ground state, such as collinear, coplanar and even non-coplanar spin orders. The phase diagram is mapped out with varying boson tunneling and Bose-Fermi interactions. Most significantly, in one non-coplanar state the mixture is found to exhibit a spontaneous quantum Hall effect in fermions and crystalline superfluidity in bosons, both driven by interaction.

Coherent Heteronuclear Spin Dynamics in an Ultracold Spinor Mixture

“…Finally, similar dynamics should exist in other ultracold spinor mixtures. In fact, a proposal for realizing the spontaneous quantum Hall effect and a chiral superfluid with the Bose-Fermi spinor mixture was made recently [49].…”

Chiral spin condensation in a one-dimensional optical lattice

“…In Bose-Fermi mixtures, chiral spin condensate of bosons may provide a background for the fermions to form topological phases. The prospect of inducing topological phases from spontaneous symmetry breaking [42][43][44][45][46] is worth further exploration.…”

Polarizing the Medium: Fermion-Mediated Interactions between Bosons

“…On the experimental side, tremendous progress have been achieved, which include controlling and characterizing the interspecies interactions [4][5][6][7][8][9][10][11][12], realizing mixture of Bose and Fermi superfluids [13][14][15][16][17], and probing physics of the phase separation state [18,19]. On the theoretical side, intense attentions have been paid to study groundstate properties [20][21][22][23][24][25][26], nature of excitations [26][27][28][29][30], boson-mediated fermionic superfluidity [31][32][33][34][35], collective dynamics [36,37], and formation of exotic quantum phases [38][39][40][41][42][43][44].…”