PHYSICAL REVIEW B 105, 195439 (2022) Jacutingaite family: An efficient platform for coexistence of spin valley Hall effects, valley spin-valve realization, and layer spin crossover Majeed Ur Rehman, Maryam Kiani, and Jian Wang * College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, Guangdong 518060, China (Received 1 March 2022; accepted 3 May 2022; published 31 May 2022) Jacutingaite family, a family of naturally occurring exfoliable minerals (Pt 2 HgSe 3 and Pd 2 HgSe 3 ) discovered in Brazil, is recently predicted to be the very first large-gap Kane-Mele quantum spin Hall insulators. However, yet to date, the door is locked for realizing versatile spin-valley based phenomena due to inversion symmetry in this family. By exploiting the inversion symmetry using different strategies such as placing the jacutingaite family in the vertical electric field or growing its composites with some suitable well-matched systems, we reveal several promising valley spin based phenomena in the jacutingaite family. Overall, we achieve the coupled spin valley Hall effect, valley spin-valve effect, Rashba spin splitting around the low-symmetric M point, layer crossover accompanied by spin crossover, and selective-excitation of carriers from opposite valleys in this family. More interestingly, swapping of the induced spin splittings, Berry curvatures, and the spin texture between the two valleys occur upon the reversal of electric field from E z > 0 to E z < 0 without destroying the Z 2 topological hallmarks. Meanwhile, considerable hexagonal trigonal warping effects around the K + and K − valleys are realized. Furthermore, by applying vertical electric field through interfacial coupling with ferroelectric III 2 − VI 3 film, valley contrasting Berry curvature in the Pt 2 HgSe 3 layer with a larger spin splitting in the lower conduction band (∼188 meV) is achieved in the +P polarization state. By inverting the polarization state from +P to −P, the Fermi level shifts down into the valence band of the Pt 2 HgSe 3 layer (∼82 meV) revealing a hole doping in the Pt 2 HgSe 3 layer. This could establish an effective mechanism to control doping levels in the Pt 2 HgSe 3 layer as desirable for achieving superconductivity at finite doping in the jacutingaite family. Our paper provides a path towards integrating valleytronics and spintronics in multivalley materials with broken inversion symmetry. DOI: 10.1103/PhysRevB.105.195439 I. INTRODUCTION Recently, two-dimensional solids crystallized in the hexag- onal lattice geometry, especially after the experimental isolation of graphene in 2004 [1] and its-like structures such as germanene and stanene etc. (also referred to as two-dimensional Xenes), have drawn great attention due to offering a versatile platform for the manipulation of charge, spin, and valley degrees freedom in the topological spintronic and valleytronics context [2–8]. The Xene solids follow the famous Kane-Mele topological model [2,9]. However, the weak spin-orbit coupling effects in graphene (λ SO ∼ 40 μeV) and other Xene materials limit their practical applications. By further efforts, the researcher discovered a new family of the so-called transition metal dichalcogenides with strong spin-orbit coupling, offering a comparatively better platform for manipulating spin and valley-dependent properties as highly demandable for spintronic and valleytronics applica- tions [10–13]. The recent discovery of the jacutingaite family (Pt 2 HgSe 3 and Pd 2 HgSe 3 ) is considered as an alternative of Xene family in the topological and valleytronics context. It is be- cause jacutingaite family follows the same topological model * Correspondence author: jianwang@hku.hk (Kane-Mele) as Xene solids do [14]. However, this family host strong spin-orbit coupling effects (λ SO ∼ 21 meV) as compared to graphene and is very suitable for spin and val- ley related practical applications [15–17]. Very recently, it has been shown that (Pt /Pd) 2 HgSe 3 is Z 2 topological insu- lator with large nontrivial band gap ∼0.5eV [14]. So far, two members of this family, Pt 2 HgSe 3 and Pd 2 HgSe 3 have been experimentally synthesized in the bulk form [18]. Very recently, this family has been studied in the free-standing form with inversion symmetry as well as on magnetic sub- strate for the phenomena like quantum spin Hall (QSH) and valley-polarized quantum anomalous Hall effects respectively [15,19–22]. However, yet to date, the door is closed for various val- ley spin based phenomena due to the presence of inversion symmetry in the jacutingaite family. In this context, a detailed exploration on the consequences of the broken inversion sym- metry in the jacutingaite family is clearly needed. This type of study is important because it may unlock the door for phe- nomena based on spin-valley locking and valley contrasting Berry curvature in the (Pt /Pd) 2 HgSe 3 layers. In particular, it can reveal several interesting phenomena such as coexistence of quantum spin and quantum valley Hall (QVH) effects (i.e., quantum spin-valley Hall effect), valley-spin locking such as valley spin-valve effects, Rashba and valley Zeeman-type spin splitting in the jacutingaite family. 2469-9950/2022/105(19)/195439(12) 195439-1 ©2022 American Physical Society