Landau levels induced by pseudo-magnetic field in strained topological crystal insulator SnTe thin films

Topological crystalline insulators (TCI) are a class of new quantum phases with their non-trivial topology arisen from crystalline symmetries. One of unique properties of TCIs is the highly tunability under external strain, which can break the crystalline symmetries and hence manipulate the nontrivial topological boundary states. Typically, strain can be used to realize many novel phenomena, such as the mass generation at Dirac points, as well as topological phase transitions. Here, by mean of molecular beam epitaxy, we successfully grow SnTe thin films on SrTiO₃ substrate to fabricate a strained TCI system. Interestingly, pseudo Landau quantization is observed in this system for the first time, induced by a strong uniaxial strain with inhomogeneity. The extracted pseudo magnetic field is estimated to over 100 Tesla, which is the highest record ever reported in the family of the Dirac-cone like linear dispersed surface states materials. Our findings may support the newly developed research field of ‘strain engineering’.