Phases and phase transtions in one-dimensional alternating mixed spin (1/2-1) chain: effects of frustration and anisotropy

TL;DR

This study explores how frustration and anisotropy influence phase transitions in a one-dimensional mixed-spin chain, revealing new magnetic phases and the effects of these parameters using advanced numerical methods.

Contribution

It provides a comprehensive analysis of phase behavior in mixed-spin chains under combined frustration and anisotropy, identifying novel phases and transitions not previously characterized.

Findings

Moderate frustration induces a transition from ferrimagnetic to antiferromagnetic phase.

Weak easy-plane anisotropy destabilizes ferrimagnetic order and promotes antiferromagnetic phase.

Strong frustration and anisotropy lead to a spin density wave-like phase.

Abstract

We investigate the phases and phase-transitions in one-dimensional alternating mixed-spin (1/2-1) chain in the presence of both frustration and anisotropy. Frustration is introduced via next-nearest-neighbor interactions, while single-ion anisotropy is incorporated at each lattice site. Our results show that moderate frustration can drive a phase transition from a ferrimagnetic state to an anti-ferromagnetic ground state. Remarkably, the presence of a weak easy-plane anisotropy destabilizes the ferrimagnetic order, also leading to the emergence of an antiferromagnetic phase. Interestingly, under strong frustration and anisotropy, the system exhibits signatures of a novel phase with spin density wave (SDW)-like modulation . We explore these anomalous phase transitions by employing exact diagonalization (ED) for small system sizes and the density matrix renormalization group (DMRG) method to characterize ground state properties for larger system sizes. We also investigate the finite-temperature behavior across various phases using the ancilla-based time-evolving block decimation (TEBD) approach. The primary objective of this work is to elucidate the phase structure of alternating mixed-spin chains under the combined effects of frustration and anisotropy. The primary objective of this work is to elucidate the intricate interplay between frustration and anisotropy in identifying the exotic phases and phase-transitions in alternating mixed-spin chains. Our findings contribute to a deeper understanding of mixed-spin quantum systems and may offer insights for future theoretical and experimental studies.