Unconventional spin excitations in the S=32 triangular antiferromagnet RbAg2Cr[VO

Abstract

We present muon spin relaxation (μSR) measurements of the S = 3/2 undistorted triangular lattice established in RbAg 2 Cr[VO 4 ] 2. The zero-(ZF) and longitudinal-field μSR spectra evidence the absence of spin freezing and long-range magnetic ordering down to T = 25 mK, supporting the formation of a dynamic ground state. Noticeably, we observe an anomalous temperature dependence of the ZF muon spin relaxation rate λ ZF (T), featuring a decrease below T = 20 K. This suggests the alteration of the dominant relaxation mechanism by the development of short-range magnetic correlations. A subsequent leveling off of λ ZF (T) below T = 2 K indicates persistent spin dynamics and reveals the presence of exotic magnetic excitations. The field dependence of the muon spin relaxation rate at T = 25 mK is well described by a diffusive spin transport model with algebraic spin-spin correlations. The suppressed long-range order and the peculiar temperature-dependent behavior of λ ZF (T) will be discussed in terms of the exchange interaction between Cr 3+ moments via nonmagnetic [VO 4 ] 3− entities. In the title compound, the degeneracy of the t 2g-orbital set is not lifted by a space group symmetry reduction or subject to significant anisotropy resulting from spin-orbit coupling.

Collinear antiferromagnetic order in spin-$\frac52$ triangle lattice antiferromagnet Na$_3$Fe(PO$_4$)$_2$

“…Therefore, Ag 3 Cr(VO 4 ) 2 (space group: C2/c) is a distorted/anisotropic TLA with a collinear AFM ordering below T N 10 K, whereas the other compounds (A = K, Rb) with higher symmetry (space group: P 3) are undistorted/isotropic TLAs and are reported show signature of QSL [36]. Several other compounds with higher symmetry in this series also feature isotropic triangular lattices [28,32,33,36,56]. As pointed out in Fig.…”

“…Similarly, the monoclinic (C2/c) compound BaNa 2 Cu(VO 4 ) 2 features antiferromagnetic spin-1/2 crossed chains arranged 62 • with respect to each other [26]. Moreover, the signature of QSL is reported in the structurally perfect spin-1/2 TLA BaNa 2 Co(PO 4 ) 2 [35] and spin-3/2 TLAs (K,Rb)Ag 2 Cr(VO 4 ) 2 [33,36], piquing further interest in this series of compounds. Thus, this series of materials serve as a cradle for novel ground states where one can tune the ground state properties by changing the chemical pressure.…”

“…Recently, a series of compounds with general formula AA M (XO 4 ) 2 (A = Ba, K, Rb, and Sr, A = Na 2 and Ag 2 , M = Mn, Ni, Co, Cr, Fe, and Cu, and X = P and V) are reported with varying crystal structures [26][27][28][29][30][31][32][33][34]. Interestingly, this series of compounds are projected as low-dimensional spin systems where the superexchange takes place in an elongated path involving VO 4 or PO 4 units.…”

Quasi-one-dimensional magnetism in the spin- 12 antiferromagnet BaNa2Cu(VO4)2Sebastian1, Somesh2, Nandi3 et al. 2021Phys. Rev. B21080View full textAdd to dashboardCite

“…Recently, synthesis and magnetic properties of a series of compounds AA M(VO 4 ) 2 (A = Ba and Sr, A = Na 2 and Ag 2 , and M = Mn, Ni, Co, Fe, and Cu) were reported. Despite some variations in their crystal structures, the magnetic model of anisotropic triangular lattice has been generally used to understand their magnetism [12][13][14][15][16][17][18]. BaAg 2 Cu(VO 4 ) 2 stands as an exception in this series, because its crystal structure is triclinic (space group: P1) [12], and indeed microscopic analysis via density-functional band-structure calculations [19] combined with resonance spectroscopy [20] revealed 1D magnetism with two dissimilar types of spin chains, one ferromagnetic and one antiferromagnetic, coexisting in the structure.…”

Quasi-one-dimensional magnetism in the spin-$\frac12$ antiferromagnet BaNa$_{2}$Cu(VO$_{4}$)$_{2}$

“…Recently, synthesis and magnetic properties of a series of compounds AA ′ M (VO 4 ) 2 (A = Ba and Sr, A ′ = Na 2 and Ag 2 , and M = Mn, Ni, Co, Fe, and Cu) were reported. Despite some variations in their crystal structures, the magnetic model of anisotropic triangular lattice has been generally used to understand their magnetism [12][13][14][15][16][17][18]. BaAg 2 Cu(VO 4 ) 2 stands as an exception in this series, because its crystal structure is triclinic (space group: P 1) [12], and indeed microscopic analysis via density-functional band-structure calculations [19] combined with resonance spectroscopy [20] revealed 1D magnetism with two dissimilar types of spin chains, one ferromagnetic and one antiferromagnetic, coexisting in the structure.…”