Strong Suppression of Magnetic Ordering in an S = 1/2 Square-Lattice Heisenberg Antiferromagnet Sr2CuTeO6

TL;DR

This study investigates Sr2CuTeO6, a square-lattice S=1/2 Heisenberg antiferromagnet, revealing a significantly suppressed magnetic ordering temperature due to weak interlayer exchange interactions.

Contribution

It provides experimental and theoretical evidence of suppressed magnetic ordering in Sr2CuTeO6, highlighting the role of weak interlayer exchange in this compound.

Findings

Magnetic ordering temperature TN = 4.8 K is much lower than similar compounds.

Exchange constants estimated as J1/kB ~ 80 K and J2/J1 < 0.07.

Weak interlayer exchange causes strong suppression of magnetic order.

Abstract

We report the magnetic susceptibility and the low-temperature specific heat of a double perovskite compound, Sr2CuTeO6, which is expected as the spin-1/2 square-lattice Heisenberg antiferromagnet with nearest-neighbor J1 and next-nearest-neighbor J2 exchange interactions. The specific heat exhibits a sharp lambda-like anomaly at TN = 4.8 K indicative of magnetic ordering, which is much lower than those in isostructural A2CuMO6 with A = Ba, Sr and M = W, Mo. This indicates the strong suppression of magnetic ordering in Sr2CuTeO6. We estimate the exchange constant J1/kB ~ 80 K and J2/J1 < 0.07 from magnetic susceptibility data using Pade approximation of high temperature expansion and quantum Monte Carlo method. The strong suppression of magnetic ordering in Sr2CuTeO6 should be ascribed to the weekness of the interlayer exchange.