Observation of S  = 1/2 quasi-1D magnetic and magneto-dielectric behavior in a cubic SrCuTe₂O₆

We investigate the magnetic, thermal, and dielectric properties of SrCuTe₂O₆, which is isostructural to PbCuTe₂O₆, a recently found, Cu-based 3D frustrated magnet with a corner-sharing triangular spin network having dominant first and second nearest neighbor (nn) couplings (Koteswararao et al 2014 Phys. Rev. B 90 035141). Although SrCuTe₂O₆ has a structurally similar spin network, the magnetic data exhibit the characteristic features of a typical quasi-1D magnet, which mainly resulted from the magnetically dominant third nn coupling, uniform chains. The magnetic properties of this system are studied via magnetization (M), heat capacity (C _p), dielectric constant (${\epsilon }^{{}^{\prime }}$), and measurements along with ab initio band structure calculations. The magnetic susceptibility $\chi \left(T\right)$ data show a broad maximum at 32 K and the system orders at low temperatures $T_{N1}\approx 5.5$ K and $T_{N2}\approx 4.5$ K, respectively. The analysis of the $\chi \left(T\right)$ data gives an intra-chain coupling, $J_3/k_{\text{B}}$, to be about  ≈  −  42 K with non-negligible frustrated inter-chain couplings ($J_1/k_{\text{B}}$ and $J_2/k_{\text{B}}$). The hopping parameters obtained from the LDA band structure calculations also suggest the presence of coupled uniform chains. The observation of simultaneous anomalies in ${\epsilon }^{{}^{\prime }}\left(T\right)$ at $T_{N1}$ and $T_{N2}$ suggests the presence of a magneto-dielectric effect in SrCuTe₂O₆. A magnetic phase diagram is also built based on the M, C _p, and ${\epsilon }^{{}^{\prime }}$ results. (paper)