Comparative description of magnetic interactions in Sr₂CuTeO₆and Sr₂CuWO₆

Abstract

In this work, we comparatively explored the electronic structure and the low-dimensional magnetic interactions of double-perovskite compounds SrCuTeO and SrCuWO through first-principles calculations. The electronic structure calculations indicate that the Cu (3d ) site is the only magnetic active one, whereas Te and W remain in nonmagnetic states with d and d electronic configurations, respectively. The magnetic exchange interactions have been evaluated on the basis of the classical Heisenberg model. Both SrCuTeO and SrCuWO should be strong frustrated 2D magnetism, in excellent agreement with the experimental observations. Nevertheless, the nearest-neighbor antiferromagnetic interaction J plays a determined role in constructing the Néel antiferromagnetic ordering within the square Cu framework of SrCuTeO. While, the next-nearest-neighbor antiferromagnetic interaction J transcends the nearest-neighbor interaction J, establishes the collinear antiferromagnetic ordering in SrCuWO. The discrimination has been explored and analyzed in detail using density of states, charge density as well as spin density analysis.

Exchange Interactions Mediated by Nonmagnetic Cations in Double Perovskites

“…In the case of a completely filled d-manifold (Te 6+ ) cation, the exchange path does not include any of its orbitals, but for the d 0 (W 6+ ) bridging cation, the SSE process via these empty orbitals is pivotal. While these conclusions corroborate with DFT+U based studies [16,45,49], it is important to know that the computed exchange couplings strongly depend on the choice of the Coulomb repulsion parameter U . We further provided the rationale for the observed exchange interactions, justifying with numerical evidence.…”

“…in Sr 2 CuTeO 6 , this corresponds to (J 1 , J 2 ) values being renormalized from (7.60,0.60) to (7.18,0.21) [15]. Given the qualitative similarity of the crystal structures [12,13] as well as the electronic states near the Fermi level [45], it seems surprising to find the dominant ab-plane exchange couplings reversed in the two compounds -J 1 in Sr 2 CuTeO 6 and J 2 in Sr 2 CuWO 6 . It is important to note that the states above (unoccupied) and below (doubly occupied) the Fermi level play an active role in the superexchange process, particularly, if these states belong to the ions bridging the two magnetic sites.…”

Site-Selective d10/d0 Substitution in an S = 1/2 Spin Ladder Ba2CuTe1–xWxO6 (0 ≤ x ≤ 0.3)

“…17,18 Following the principles of the d 10 /d 0 effect, Sr2CuTeO6 is Néel ordered, while a strong J2 leads to columnar ordering for Sr2CuWO6. 16,19,[21][22][23][24] Upon introducing a mixture of W 6+ and Te 6+ , the material evades ordering over a wide portion (x = 0.05 -0.6) of the Sr2CuTe1-xWxO6 solution. 7,10,[25][26][27][28] The 50:50 mixture Sr2CuTe0.5W0.5O6 closely resembles a quantum spin-liquid, an exotic magnetic state where the moments remain dynamic at zero Kelvin and have been highly sought since they were first proposed in the 1970s.…”

Spin-liquid-like state in a spin-1/2 square-lattice antiferromagnet perovskite induced by d10–d0 cation mixing

“…This dramatic change in exchange interactions is driven by differences in orbital hybridization. In Sr2CuWO6 the dominant 180° Cu-O-W-O-Cu J2 exchange pathway is enabled by significant W 5d 0 -O 2p hybridization 19,25 . In contrast, the filled 4d 10 states in Sr2CuTeO6 are core-like and do not hybridize 18,25 resulting in a weak J2.…”

“…In Sr2CuWO6 the dominant 180° Cu-O-W-O-Cu J2 exchange pathway is enabled by significant W 5d 0 -O 2p hybridization 19,25 . In contrast, the filled 4d 10 states in Sr2CuTeO6 are core-like and do not hybridize 18,25 resulting in a weak J2. The origin of the dominant 90° J1 interaction is under debate: Babkevich et al 18 proposed a Cu-O-O-Cu exchange pathway without a contribution from Te, whereas Xu et al 25 proposed that some Te 5p -O 2p hybridization does occur affecting the J1 interaction.…”