Magnetic field modulated photoelectric devices in ferromagnetic semiconductor CrXh (X = S/Se, h = Cl/Br/I) van der Waals heterojunctions

Abstract

The interactive control between electron charge and spin is essential to spintronics. Two-dimensional (2D) ferromagnetic semiconductors (FMSs) are a kind of unique candidate materials that could lead to flexible magnetoelectric and magneto-optic applications. In this Letter, we construct a series of van der Waals heterostructures by 2D magnetic CrXh (X = S/Se, h = Cl/Br/I) monolayers. Based on first-principles calculations, both monolayers and heterostructures have been demonstrated as intrinsic FMSs with large magnetic moments, suitable bandgaps, good carrier mobility, and high Curie temperatures. Taking advantage of the heterojunction effect, one can precisely control the charge transport behavior by forming three types of band alignments. Under an external alternating magnetic field, CrSeBr/CrSeCl and CrSBr/CrSI heterostructures can reversibly reconfigure between type-II and type-I band alignments upon switching of the spin direction. Combining the robust magnetic ordering and distinctive spin-polarized band alignment, our designed CrXh based magnetic heterostructures are ideal candidates for innovative magnetic-field-modulated photoelectric devices for realizing ultrarapid and reversible “write-read” processes.

Calculated magnetic exchange interactions in the van der Waals layered magnet CrSBr

“…In recent years, ternary chromium thiohalide compound CrSBr has been extensively studied [19][20][21][22][23][24][25][26][27][28][29][30][31][32]. CrSBr is a 2D magnetic material with a van der Waals (vdW) layered structure along the c axis [22].…”

Enhanced ferromagnetism, perpendicular magnetic anisotropy and high Curie temperature in the van der Waals semiconductor CrSeBr through strain and doping

“…The generalized gradient approximation under the Perdew-Burke-Ernzerhof (PBE) functional was considered for treating the exchange correlation, [52][53][54] and the spin-polarized GGA+U method with U eff = 3.0 eV was adopted to describe the strong correlation and electron interaction of the Cr-3d orbitals. [9][10][11][12][13][14][19][20][21][22][23][24][25][26][27][28] The Heyd-Scuseria-Ernzerhof (HSE06) hybridized functional was selected to accurately model the electronic structure and density of states (DOS). A 480-eV cutoff energy was adopted for the plane waves.…”

“…Recently, Cr-based 2D vdW FMS CrXY (X = O, S, Se; Y = F, Cl, Br, I) monolayers [4][5][6][7][8][9][10][11][12][13][14] with intrinsic ferromagnetism have been developed and widely studied, both theoretically and experimentally, due to their unique physical properties associated with their reduced dimensionality. Specifically, (i) systems with a layered structure which belong to the Pmmn space group, have been widely studied for nearly 50 years; 15 (ii) 2D vdW CrXY monolayers with a rectangular spin lattice have been found to exhibit a significantly higher T C , than monolayer CrI 3 and bilayer Cr 2 Ge 2 Te 6 with a honeycomb spin lattice; 5 (iii) bulk and monolayer CrOCl and CrSBr have been obtained experimentally and have been reported to possess excellent air stability as well as to be easily pliable and cleavable; [6][7][8] (iv) 2D vdW CrXY monolayers have been shown to exhibit triaxial magnetic anisotropy, [9][10][11][12][13] which may provide more degrees of freedom for designing spintronic devices. Despite these recent and extensive investigations on 2D vdW CrXY monolayers, their T C has remained below room temperature and these monolayers have been found to mostly have small in-plane anisotropy energy, which hiders their application in practical spintronic devices.…”

“…Furthermore, monolayer CrSeBr also possesses excellent stability, a large spin-wave excitation gap (0.78 eV), and a high T C (150 K). 13,20,29 To date, there has been no study on the control of the MAE and T C of monolayer CrSeBr via strain and carrier doping.…”

Recent research advances in two-dimensional magnetic materials

“…王金兰课题组 [173] 运用第一性原理计算在二维铁磁 半导体异质结中设计了一种光电器件. 在外加磁场 改变异质结磁化方向前后, 其自旋向上和向下的两 个通道能级排列不同, 可使其在Type-I和Type-II型能带排列类型间转变, 有可能在一定的光照条 件下可逆地调控器件的"开关"状态, 达到磁-光-电 三者协同调控的目的.…”