Transition metal disulfides 4Hb-Ta(S, Se)2 with natural heterostructure of 1T- and 1H-Ta(S, Se)2 layers have became the focus of correlated materials their unique combinations of Mott physics and possible topological superconductivity. In this work, we study the upper critical fields mu0Hc2 of 4Hb-TaS2 and 4Hb-TaS1.99Se0.01 single crystals systematically. Transport measurements up to 35 T show that both of ab-plane and c-axis upper critical fields (mu0Hc2,ab and mu0Hc2,c) for 4Hb-TaS2 and 4Hb-TaS1.99Se0.01 exhibit a linear temperature dependent behavior down to 0.3 K, suggesting the three-dimensional superconductivity with dominant orbital depairing mechanism in bulk 4Hb-Ta(S, Se)2. However, the zero-temperature mu0Hc2,ab(0) for both crystals are far beyond the Pauli paramagnetic limit mu0HP. It could be explained by the effects of spin-momentum locking in 1H-Ta(S, Se)2 layers with local inversion symmetry broken and the relatively weak intersublattice interaction between 1H layers due to the existence of 1T layers.
@article{arxiv.2312.03448,
title = {Extreme orbital ab-plane upper critical fields far beyond Pauli limit in 4Hb-Ta(S, Se)2 bulk crystals},
author = {Fanyu Meng and Yang Fu and Senyang Pan and Shangjie Tian and Shaohua Yan and Zhengyu Li and Shouguo Wang and Jinglei Zhang and Hechang Lei},
journal= {arXiv preprint arXiv:2312.03448},
year = {2025}
}