Structure and magnetic properties of a family of two-leg spin ladder compounds Ba2RE2Ge4O13 (RE = Pr, Nd, and Gd-Ho) with strong rung interaction

TL;DR

This paper explores a family of rare-earth-based spin ladder compounds Ba2RE2Ge4O13, revealing their strong rung interactions, magnetic properties, and potential for studying novel 4f electron spin ladder physics.

Contribution

It reports the synthesis, structure, and magnetic properties of Ba2RE2Ge4O13 compounds with detailed analysis of their spin ladder behavior and magnetic interactions.

Findings

All compounds show dominant antiferromagnetic interactions.

Ba2Dy2Ge4O13 exhibits spin dimerization and long-range AFM order.

The compounds are strong-rung spin ladder systems.

Abstract

Compared to the intensive investigation on the 3d transition-metal (TM)-based spin ladder compounds, less attention has been paid to the ones constructed by the rare-earth (RE) ions. Herein, we report a family of RE-based spin ladder compounds Ba2RE2Ge4O13 (RE = Pr, Nd, Gd-Ho) crystallized into the monoclinic structure with the space group C2/c. The RE ions are arranged on a two-leg spin ladder motif along the b-axis, where the rung and leg exchange interactions are bridged via the RE-O-RE pathways and RE-O-Ge-O-RE routes, respectively. Moreover, the much shorter rung distance in the RE2O12 dimer units than the leg distance suggests Ba2RE2Ge4O13 to be a strong-rung spin ladder system. All the synthesized Ba2RE2Ge4O13 (RE = Pr, Nd, Gd-Ho) compounds exhibit the dominant antiferromagnetic (AFM) interactions and absence of magnetic order down to 1.8 K. Among the family members, Ba2Dy2Ge4O13 can be described by Jeff = 1/2 Kramers doublet states, the low temperature specific heat indicates the coexistence of spin dimerized state with broad maximum at ~ 2.4 K and long-range AFM order with TN = 0.81 K. This family of Ba2RE2Ge4O13 compounds thereby provides a rare platform to investigate the novel spin ladder physics constructed by 4f electrons.