The planar triangular $S=3/2$ magnet AgCrSe${}_2$: magnetic frustration, short range correlations, and field tuned anisotropic cycloidal magnetic order

Abstract

Our studies evidence an anisotropic magnetic order below $T_N=32$~K. Susceptibility data in small fields of about 1~T reveal an antiferromagnetic (AFM) order for $H\perp c$, whereas for $H\parallel c$ the data are reminiscent of a field-induced ferromagnetic (FM) structure. At low temperatures and for $H\perp c$, the field-dependent magnetization and AC susceptibility data evidence a metamagnetic transition at $H^{+}=5$~T, which is absent for $H\parallel c$. We assign this to a transition from a planar cycloidal spin structure at low fields to a planar fan-like arrangement above $H^{+}$. A fully FM polarized state is obtained above the saturation field of $H_{\perp S}=23.7$~T at 2~K with a magnetization of $M_s=2.8$~${\mu }_{\mathrm{B}}/Cr$. For $H\parallel c$, $M(H)$ monotonously increases and saturates at the same $M_s$ value at $H_{\parallel S}=25.1$~T at 4.2~K. Above $T_N$, the magnetic susceptibility and specific heat indicate signatures of two dimensional (2D) frustration related to the presence of planar ferromagnetic and antiferromagnetic exchange interactions. We found a pronounced nearly isotropic maximum in both properties at about $T^{\ast }=45$~K, which is a clear fingerprint of short-range correlations and emergent spin fluctuations. Calculations based on a planar 2D Heisenberg model support our experimental findings and suggest a predominant FM exchange among nearest and AFM exchange among third-nearest neighbors. Only a minor contribution might be assigned to the antisymmetric Dzyaloshinskii-Moriya interaction possible related to the non-centrosymmetric polar space group $R3m$. Due to these competing interactions, the magnetism in AgCrSe${}_2$, in contrast to the oxygen based delafossites, can be tuned by relatively small, experimentally accessible, magnetic fields, allowing us to establish the complete anisotropic magnetic $H-T$ phase diagram in detail.

References in corpus (13)

• The electronic properties of graphene
• Spin-driven ferroelectricity and possible antiferroelectricity in triangular lattice antiferromagnets ACrO2 (A = Cu, Ag, Li, or Na)
• The properties of ultrapure delafossite metals
• Field-induced instability of the quantum-spin-liquid ground state in the $J_{\mathrm{eff}}=\frac{1}{2}$ triangular-lattice compound NaYbO${}_2$
• Frustrated two dimensional quantum magnets
• Critical behavior of the metallic triangular-lattice Heisenberg antiferromagnet PdCrO2
• Unusual magnetism of layered chromium sulfides MCrS2 (M=Li, Na, K, Ag, and Au)
• Quantum fluctuations in anisotropic triangular lattices with ferro- and antiferromagnetic exchange
• Structure and magnetism of Cr2BP3O12: Towards the quantum-classical crossover in a spin-3/2 alternating chain
• Magnetic phases of quasi-two-dimensional antiferromagnet on triangular lattice CuCrO${}_2$
• Anisotropic electron spin resonance of YbIr2Si2
• Ultrahigh Magnetic Field Phases in Frustrated Triangular-lattice Magnet CuCrO${}_2$
• Large Magnetic-Field-Induced Strain at the Magnetic Order Transition in Triangular Antiferromagnet AgCrS2

Cited by in corpus (1)

• Spin-orbit-derived giant magnetoresistance in a layered magnetic semiconductor AgCrSe2