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Two-dimensional transition metal dichalcogenides MX 2 ( M = W, Mo, Nb, and X = Te, Se, S) with strong spin–orbit coupling possess plenty of novel physics including superconductivity. Due to the Ising spin–orbit coupling, monolayer NbSe 2 and gated MoS 2 of 2 H structure can realize the Ising superconductivity, which manifests itself with in-plane upper critical field far exceeding Pauli paramagnetic limit. Surprisingly, we find that a few-layer 1 T d structure MoTe 2 also exhibits an in-plane upper critical field which goes beyond the Pauli paramagnetic limit. Importantly, the in-plane upper critical field shows an emergent two-fold symmetry which is different from the isotropic in-plane upper critical field in 2 H transition metal dichalcogenides. We show that this is a result of an asymmetric spin–orbit coupling in 1 T d transition metal dichalcogenides. Our work provides transport evidence of a new type of asymmetric spin–orbit coupling in transition metal dichalcogenides which may give rise to novel superconducting and spin transport properties.

2D materials with multi-phase and multi-element crystals such as transition atoms (V-, Cr-, Mn-, Fe-, Cd-, Pt-, and Pd-) based chalcogenides (TMCs) and phosphorous chalcogenides (TMPCs), offer a unique platform to explore novel physical phenomena including 2D ferromagnetism, 2D superconductivity, high-Tc topological superconductivity, Majorana bound states, and many-body excitons 1-9 . However, synthesis of a singlephase/composition of these 2D crystals is still challenging since the growth kinetics is difficult to be controlled during chemical vapor deposition (CVD) 10 . Here, we unravel a competitive-chemical reaction growth mechanism via controlling the kinetic parameters to manipulate the nucleation and growth rate. Based on this mechanism, chemical reactions of 2D crystals with the defined phase, controllable structure, and tunable component can be realized. Specifically, we synthesized 67 types of 2D compounds including 27 binary metal chalcogenides with different chemical compositions, 12 ternary metal phosphorous chalcogenides, 24 alloys, and 4 heterostructures. The ferromagnetism and superconductivtity in FeXy can be tuned with y value, such as superconductivity observed in FeX and ferromagnetism in the FeS2 monolayers, demonstrating the high quality of as-