Observation of ferromagnetic ordering in a stable α−Co(OH)2 phase grown on a MoS2

Transition from antiferromagnetic to ferromagnetic β-Co(OH)2 with higher Curie temperature

“…In the β-Ni(OH) 2 /MoS 2 system we have achieved ferromagnetic ordering with the highest transition temperature of 26 K and the maximum coercivity of about 2925 Oe at temperature 2 K [11]. In α-Co(OH) 2 /MoS 2 system we have achieved soft ferromagnetism having the highest transition temperature of 117 K and the maximum coercivity of about 176 Oe at temperature 2 K [12]. In β-Co(OH) 2 /MoS 2 system we have obtained ferromagnetic ordering with the highest transition temperature of 10 K and the maximum coercivity of amount 1277 Oe at 2 K [12].…”

“…In α-Co(OH) 2 /MoS 2 system we have achieved soft ferromagnetism having the highest transition temperature of 117 K and the maximum coercivity of about 176 Oe at temperature 2 K [12]. In β-Co(OH) 2 /MoS 2 system we have obtained ferromagnetic ordering with the highest transition temperature of 10 K and the maximum coercivity of amount 1277 Oe at 2 K [12]. As the origin of the ferromagnetism at the interface is the effect of the charge-transfer from the 2D nonmagnetic material (MoS 2 or WS 2 ) to the antiferromagnetic materials (Ni(OH) 2 or Co(OH) 2 ), therefore the strength of the ferromagnetic ordering largely depends on the extent of the charge-transfer.…”

“…But the scientific community debates about the origin of the magnetic signal and the feasibility of this approach whether it can produce the long-range magnetic ordering [8][9][10]. To overcome this issue and enhance the magnetic properties (the coercivity and the ferromagnetic transition temperature), one of the most elegant approaches to develop a reliable and feasible semiconducting ferromagnet is to grow an antiferromagnetic layer on a thin sheet of a twodimensional nonmagnetic material and create ferromagnetism by using the charge-transfer effect [11,12]. In order to exercise this approach, in the previous work we have achieved ferromagnetism by growing different antiferromagnetic materials like β-Ni(OH) 2 [11], α-Co(OH) 2 [12], and β-Co(OH) 2 [12] on the surface of a MoS 2 sheet.…”

“…To overcome this issue and enhance the magnetic properties (the coercivity and the ferromagnetic transition temperature), one of the most elegant approaches to develop a reliable and feasible semiconducting ferromagnet is to grow an antiferromagnetic layer on a thin sheet of a twodimensional nonmagnetic material and create ferromagnetism by using the charge-transfer effect [11,12]. In order to exercise this approach, in the previous work we have achieved ferromagnetism by growing different antiferromagnetic materials like β-Ni(OH) 2 [11], α-Co(OH) 2 [12], and β-Co(OH) 2 [12] on the surface of a MoS 2 sheet. In the β-Ni(OH) 2 /MoS 2 system we have achieved ferromagnetic ordering with the highest transition temperature of 26 K and the maximum coercivity of about 2925 Oe at temperature 2 K [11].…”

Nickel-Doped Silver Sulfide: An Efficient Air-Stable Electrocatalyst for Hydrogen Evolution from Neutral Water

“…There are inadequate reports available on the electrocatalytic activity of Ag 2 S. 27−30 In addition, chemical doping of metal chalcogenides with transition metals to tune the physical properties is an elegant approach. 31,32 It has been proposed that transition metal (Fe, Ni, Co) doping adjacent to sulfur edge sites can enhance the HER activity by lowering the hydrogen adsorption free energy (Δ G H ). Density functional theory calculations also support this fact.…”