Three-dimensional ferrimagnetic ground state of triangular-lattice system Ca3Co2O6

TL;DR

This study investigates the magnetic phase transitions in Ca3Co2O6, revealing a 3D ferrimagnetic ground state arising from interchain interactions and impurity effects, with implications for understanding frustrated magnetic systems.

Contribution

It demonstrates the role of third-nearest-neighbor interactions and impurity substitution in stabilizing or destabilizing the 3D ferrimagnetic order in Ca3Co2O6.

Findings

Weak-FM interchain interactions remove frustration, enabling 3D FIM order at low T.

Impurity S=5/2 weakens FM interactions, destabilizing the 3D FIM state.

Hindered kinetics cause coexistence of 1D FM chains and 3D FIM state at low T.

Abstract

High temperature one-dimensional (1D) ferromagnetic (FM) chains in Ca3Co2O6 spin system are subjected to a magnetic field and temperature induced first order phase transition (FOPT) to 3D ferrimagnetic (FIM) ground state with decrease in temperature (T). Weak-FM interaction of third nearest-neighbor(nn) interchain removes the frustration effect arising from antiferromagnetic (AFM) interactions of first-nn and second-nn interchains in the underlying triangular-lattice resulting a 3D FIM ordering of 1D FM chains at low T. However, hindered kinetics of FOPT partially masks this tranformation giving rise to coexistence of non-interacting 1D FM chains with 3D-FIM state at low-T. The existence of all these couplings is further confirmed here by random substitution of S = 5/2 magnetic-impurity into the spin chain of original system. It reveals weakening of FM interactions of both intrachain and third-nn surrounding chains respectively without significant modulation in the AFM coupling of first-nn and second-nn interchains. Thus, influence of AFM interactions is enhanced as compared to effective FM coupling with increase of S = 5/2 impurity content resulting instability of 3D long-range FIM state at low-T.