Anomalous spin dynamics in the coupled spin tetramer systemCuSeO3

Abstract

We report high-field magnetization, high-frequency electron spin resonance (ESR), and 77 Se nuclear magnetic resonance (NMR) measurements on the linear spin tetramer system CuSeO 3 , consisting of strongly interacting Cu(1) dimers and weakly coupled Cu(2) spins. The magnetization exhibits anisotropic half-step magnetization plateaux at µ 0 H = 45 T, depending on a crystallographic orientation. A temperature dependence of the ESR linewidth ∆H pp in a paramagnetic phase points towards the significance of anisotropic exchange interactions. Below T N = 9 − 10 K long-range magnetic order is evidenced by the observation of a critical divergence of both ∆H pp (T ) and the nuclear spin-lattice relaxation rate 1/T 1 . In addition, we identify a magnetic anomaly at T * = 6.0(5) K below T N , which is caused by a spin reorientation. The nuclear spin-spin relaxation rate 1/T 2 unveils the development of site-specific spin correlations. The intriguing magnetism of CuSeO 3 is discussed in terms of the energy hierarchy of Cu(1) and Cu(2) spins in concert with additional intertetramer interactions.

Single crystal growth and structural, magnetic, and magnetoelectric properties in spin-frustrated bow-tie lattice of α-Cu5O2(SeO3)2Cl2

“…This has resulted in fascinating properties such as multiferroic, magnetoelectric effect and skyrmionic phase. 8,24,[27][28][29][31][32][33][35][36][37]40,48,50,51 Lone pair Se 4+ ions and electron negative halide atoms serve as chemical scissors that can stabilize the low-dimensional magnetic lattice with spin frustration. 12 Several compounds in the CuO-CuCl 2 -SeO 2 ternary phase diagram were identified and analyzed (see Table 1).…”

“…12,25 A lowdimensional crystal structure with anisotropic spin-induced multiferroicity was reported in the magnetic layers of a Cu 3 Bi(-SeO 3 ) 2 O 2 Cl 2 system. 26 In this context, compounds from the CuO-CuCl 2 -SeO 2 ternary phase diagram have been reported to exhibit exotic quantum magnetic states such as skyrmions, along with unique multiferroic properties, 8,24,[27][28][29][30][31][32][33][34][35][36][37][38] as shown in Table 1.…”

Triplons, magnons, and spinons in a single quantum spin system:SeCuO3

“…From Fig. 1(a), J connects Cu 2 spins through the SeO 3 tetrahedra, a superexchange path not so far considered [31][32][33][34]. This coupled-chain character provides an immediate indication for the origin of the continuum scattering in Figs.…”

“…The S = 1/2 quantum magnet SeCuO 3 [30] has a monoclinic unit cell with space group P2 1 /n and lattice parameters a = 7.71 Å, b = 8.24 Å, c = 8.50 Å, and β = 99.12 • . Two [31], although this scenario cannot explain the magnetic susceptibility below 90 K. Recent nuclear quadrupole resonance measurements confirmed the formation of singlet states at T 200 K [32], and together with nuclear magnetic resonance, electron spin resonance, and torque magnetometry experiments [33,34] were interpreted as reflecting two essentially decoupled subsystems, the strong, local Cu 1 dimers and weakly coupled Cu 2 spins hosting magnetic order below T N = 8 K.…”

“…1) of edge-sharing plaquettes whose superexchange paths have a Cu 1 -O-Cu 1 angle of 101.9 • [31]. Including the Cu 2 d x 2 −y 2 orbitals led to the proposal of a weakly coupled network of linear (Cu 2 -Cu 1 -Cu 1 -Cu 2 ) tetramers[31], although this scenario cannot explain the magnetic susceptibility below 90 K. Recent nuclear quadrupole resonance measurements confirmed the formation of singlet states at T 200 K[32], and together with nuclear magnetic resonance, electron spin resonance, and torque magnetometry experiments[33,34] were interpreted as reflecting two essentially decoupled subsystems, the strong, local Cu 1 dimers and weakly coupled Cu 2 spins hosting magnetic order below T N = 8 K.To access the full spin dynamics of SeCuO 3 , we grew a 1 g single-crystal sample by chemical vapor transport. Thermal neutron INS measurements were performed on the IN8 spectrometer (ILL[35]) to probe the (hkh) scattering plane.…”