Magnetic Excitation in S = 1/2 Antiferromagnetic Chain CsCoCl_{3 }with IsingLike Exchange Interaction
© The Physical Society of Japan
This article is on
Magnetic Excitation in the S = 1/2 Isinglike Antiferromagnetic Chain CsCoCl_{3} in Longitudinal Magnetic Fields Studied by Highfield ESR Measurementss
(JPSJ Editors' Choice)
J. Phys. Soc. Jpn.
92,
094701
(2023)
.
The results of highfield electron spin resonance measurements in the millimeterwave to terahertz region reveal unconventional magnetic excitation in S = 1/2 onedimensional antiferromagnets.
The onedimensional antiferromagnet with spin S = 1/2 has been studied since 1931 when H. Bethe proposed a method to obtain the exact eigenvalues and eigenstates of a system with isotropic Heisenbergtype exchange interactions. Research has revealed that the simple S = 1/2 onedimensional antiferromagnet exhibits rich and exotic properties originating from the manybody quantum effects. In the case of the mostinvestigated system with isotropic Heisenbergtype interactions, the quantum fluctuations destroy the longrange order, leading to a quantum critical state with algebraic decay of the spin correlation function. The magnetic excitation from this fluctuating ground state exhibits a marked contrast from that of the classical spin wave. The lowestenergy excitation in the S = 1/2 onedimensional antiferromagnet is a pair excitation of quasiparticles called spinons, which are mobile domain walls created by flipping the spins from its ground state. Under external magnetic fields, the magnetic excitation becomes gapless at incommensurate wave numbers in the reciprocal lattice space. In addition, recent theory has indicated that the string states, which are characterized by complex rapidities in the Betheanzats calculations, change asymptotically to multimagnon bound states upon increasing the field, significantly contributing to the excitation spectrum.
We investigated the magnetic excitation in the S = 1/2 onedimensional antiferromagnet with Isinglike anisotropy CsCoCl_{3} through highfield electron spin resonance (ESR) spectroscopy in a wide frequency region from 130 GHz to 4.4 THz under pulsed magnetic fields up to 53 T. In contrast to the Heisenbergtype system, the antiferromagnetic order is maintained in the ground state of the S = 1/2 Isinglike onedimensional antiferromagnet at zero magnetic field, owing to magnetic anisotropy. However, by applying the magnetic field along the magnetic easy axis, the system transitions into the quantum critical state. Our ESR results demonstrate that the softening of the spinon by the external magnetic field drives this fieldinduced transition. This result suggests that the antiferromagnetic order is destroyed by the propagating domain walls induced in the ground state by the longitudinal magnetic field. Thereby, the spin chain is brought into the quantumcritical state with no longrange order. In the quantum critical state, we observe the appearance of a twostring state in the terahertz region above 2.9 THz. By increasing the magnetic fields further, to the saturation field, we can successfully observe the change in the magnetic excitation from the twostring to the twomagnon bound state, for the first time.
(Written by Shojiro Kimura on behalf of all the authors)
Magnetic Excitation in the S = 1/2 Isinglike Antiferromagnetic Chain CsCoCl_{3} in Longitudinal Magnetic Fields Studied by Highfield ESR Measurementss
(JPSJ Editors' Choice)
J. Phys. Soc. Jpn.
92,
094701
(2023)
.
Share this topic
Fields
Related Articles

Chiral Gauge Field and Topological Magnetoelectric Response in Fully SpinPolarized Magnetic Weyl Semimetal Co_{3}Sn_{2}S_{2}
Electronic transport in condensed matter
Magnetic properties in condensed matter
2024111
This study clarifies the relationship between magnetic ordering and chiral gauge fields in the ferromagnetic Weyl semimetal Co_{3}Sn_{2}S_{2}, highlighting its spintronic potential using the topological magnetoelectric responses of Weyl fermions.

Electricity Provides Cooling
Crossdisciplinary physics and related areas of science and technology
Magnetic properties in condensed matter
Structure and mechanical and thermal properties in condensed matter
20241015
Electric cooling at low temperatures is successfully achieved using a ferroelectric ferromagnetic solid instead of refrigerant gases such as fluorocarbons. 
PressureTuned Classical–Quantum Crossover in Magnetic FieldInduced Quantum Phase Transitions of a TriangularLattice Antiferromagnet
Crossdisciplinary physics and related areas of science and technology
Electron states in condensed matter
Magnetic properties in condensed matter
202495
The correspondence principle states that as quantum numbers approach infinity, the nature of a system described by quantum mechanics should match that described by classical mechanics. Quantum phenomena, such as quantum superposition and quantum correlation, generally become unobservable when a system approaches this regime. Conversely, as quantum numbers decrease, classical descriptions give way to observable quantum effects. The external approach to classical–quantum crossover has attracted research interest. This study aims to demonstrate a method for achieving such control in materials.

Unification of Spin Helicity in the Magnetic Skyrmion Lattice of EuNiGe_{3}
Magnetic properties in condensed matter
202487
In the magnetic skyrmion lattice of noncentrosymmetric EuNiGe_{3}, the original magnetic helicity, determined by the antisymmetric exchange interaction, is reversed, resulting in a unified helicity.

Antiferromagnetism Induces Dissipationless Transverse Conductivity
Electronic structure and electrical properties of surfaces and nanostructures
Electronic transport in condensed matter
Magnetic properties in condensed matter
2024724
An investigation using highquality NbMnP crystals demonstrates that the anomalous Hall conductivity arising from antiferromagnetism is dissipationless, as expected from the intrinsic mechanism.