Fe/Co Doping-Induced Metallic Transition and Enhanced Magnetic Anisotropy in Monolayer NiBr2

doi:10.16553/j.cnki.issn1000-985x.2025.0123

Abstract

Abstract: Performance regulation of two-dimensional magnetic materials is crucial for the development of nanoscale spintronic devices. To explore the modulation mechanisms of Fe/Co doping on the electromagnetic properties of monolayer NiBr₂， the influence of Fe/Co doping on the electromagnetic properties of monolayer NiBr₂ was systematically investigated by first-principles calculations. In terms of structural stability， Fe doping is more stable than monolayer NiBr₂ with the change of the chemical potential of Br. Meanwhile， Fe doping is easier to obtain monolayer NiBr₂， when the chemical potential of Br is within a specific range （-1.12 eV<μ_Br<-0.50 eV）. For electronic structures， Fe doping leads to semiconductor-to-metal transformation. In terms of magnetic properties， Fe/Co doping significantly enhances the out-of-plane magnetic anisotropy in NiBr₂. Similarly， Fe doping enhances the phase transition temperature to 63.7 K， which is 2.5 times of monolayer NiBr₂. This investigation reveals the regulation law of transition metal doping on the electromagnetic properties of monolayer NiBr₂， and provides theoretical support for the rapid development of nanoscale spintronic devices.

Key words: NiBr₂; two-dimensional magnetic material; atomic doping; phase transition temperature; electromagnetic property; magnetic anisotropy

CLC Number:

O469

WANG Rui, XIN Yanbo, YANG Guohui. Fe/Co Doping-Induced Metallic Transition and Enhanced Magnetic Anisotropy in Monolayer NiBr₂[J]. Journal of Synthetic Crystals, 2025, 54(11): 1954-1960.

Figures/Tables 5

Fig.1 Atomic structure of monolayer NiBr2 （a），（b） and Co/Fe-doped defective （c），（d） with magnetic optimization. （e） Eform of Fe/Co-doped in NiBr2. The details of defects have been highlighted by yellow region. Green， red， blue and gray balls represent the atoms of Ni， Br， Co and Fe， respectively

Table 1 Lattice constants a， c， volume V， bond length L between metal and halogen atoms， intralayer and interlayer Br—Ni—Br angles θ1 and θ2， orbital moment of Br atoms at defect sites （Odefect） and surrounding matrix sites （Oground） for Fe/Co-doped defects

	a/Å	c/Å	V/Å³	L/Å	θ₁/（°）	θ₂/（°）	O_defect/μ_B	O_ground/μ_B
NiBr₂	11.1	20	235.8	2.55	87.4	92.7	0.002	0.002
Co_Ni	11.1	20	235.8	2.57	87.6	92.4	0.003	0.003
Fe_Ni	11.1	20	235.8	2.45	87.5	92.5	0.005	0.004

Table 2 Band gap， FM→DM transition temperature （TD）， magnetic anisotropy energy （MAE）， effective electron mass （m*）， magnetic moments of metal/halogen atoms （M， μB·m-1 or μB·h-1） and magnetic ground state

Structure	E_g/eV	T_D/K	MAE/meV	m^*	M/（μ_B·m^-1）	M/（μ_B·h^-1）	Magnetic ground state
NiBr₂	1.61 （I）	25.3	2.98	0.51	1.36	0.24	FM
Co_Ni	1.62 （I）	5.3	3.16	0.57	2.45	0.23	FM
Fe_Ni	Metal	63.7	5.89	4.96 （h）	3.47	0.23	FM

Fig.2 Band structures and PDOS of CoNi （a） and FeNi （b） with SOC calculations

Fig.3 Atomic orbital contributions to the MAE in CoNi （a）~（c） and in FeNi （d）~（f）

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Fe/Co Doping-Induced Metallic Transition and Enhanced Magnetic Anisotropy in Monolayer NiBr₂

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