Realizing Spin Liquids Experimentally with Kapellasite-type Quantum Kagome Antiferromagnet
© The Physical Society of Japan
This article is on
μSR Study of Kapellasite-type Quantum Kagome Antiferromagnet CaCu3(OH)6Cl2∙0.6H2O
(JPSJ Editors' Choice)
J. Phys. Soc. Jpn. 91, 013701 (2022).
This study reports the observation of the spin fluctuation in a quantum kagome antiferromagnet CaCu3(OH)6Cl2·0.6H2O which persists down to 82 mK using the μSR technique.

At ambient pressure, water has three states depending on the temperature; gaseous (water vapor), liquid (water), and solid (ice) states. Below 0 °C, water freezes to form ice which comprises crystals with molecules arranged periodically. Electron spins, which are responsible for the magnetism of materials, have similar thermodynamic properties. In general magnets, the paramagnetic (gaseous) state is stable at high temperatures in which the electron spins have random directions, whereas when the temperature is lowered, a phase transition occurs at a certain critical temperature to the magnetically ordered (solid) state in which the electron spins exhibit a periodical alignment. The magnetically ordered (solid) state is, for instance, a ferromagnetic state in which all the electron spins are aligned in one direction or an antiferromagnetic state in which all the neighboring spins point in opposite directions. By controlling and utilizing these magnetic states, modern electronics has progressed exponentially. Recently, the "magnetic frustration" effect, which prevents such electron spins from forming a solid state, has been actively investigated, and the realization and potential applications of the spin liquid state which is "a liquid state of electron spins" caused by the frustration effect have garnered significant interest.
In a spin liquid state, the spins continue to fluctuate without freezing even at absolute zero. The most famous model of the spin liquid state is the resonant valence bond (RVB) state proposed by Nobel laureate P.W. Anderson in 1973, and its relevance to the mechanism of high-temperature superconductivity and the feasibility of quantum computing using fractional excitations and associated quantum entanglement of the spin liquid state. Therefore, the realization and clarification of the spin liquid state is one of the most important issues in modern physics.
The authors have focused on Ca-Kapellasite (CaCu3(OH)6Cl2·0.6H2O) as a model material for a quantum kagome antiferromagnet, which has a strong frustration and is expected to be an excellent candidate for the spin liquid state. The spin dynamics of this material has been investigated in detail down to the extremely low temperature of 82 mK through the μSR technique. It has been elucidated from the magnetization measurements that Ca-Kapellasite exhibits magnetic order at 7.2 K. Therefore, it appears to be a magnetic material that can be described by the mean-field approximation of classical spin systems. However, the proposed μSR experiments revealed that the spins were fluctuating even in the magnetically ordered state. This indicates the dynamic aspect of the magnetic state of a quantum kagome antiferromagnet. It is expected that the development of chemically modified samples and related materials, as well as precise measurements of the physical properties, will significantly advance the understanding of the physics of kagome spin liquids.
(Written by H. K. Yoshida on behalf of all authors)
μSR Study of Kapellasite-type Quantum Kagome Antiferromagnet CaCu3(OH)6Cl2∙0.6H2O
(JPSJ Editors' Choice)
J. Phys. Soc. Jpn. 91, 013701 (2022).
Share this topic
Fields
Related Articles
-
Shedding Light on Nonreciprocal Directional Dichroism at High Magnetic Fields in a Multiferroic Material
Dielectric, optical, and other properties in condensed matter
Magnetic properties in condensed matter
2022-1-19
Large optical nonreciprocal directional dichroism, coupled with an antiferromagnetic order parameter, is observed in a high magnetic field via magneto-optical spectroscopy combined with a pulse magnet technique.
-
Spin-Wave Dynamics in Antiferromagnets under Electric Current
Electronic transport in condensed matter
Magnetic properties in condensed matter
2021-12-28
Electric current causes a Doppler effect in spin waves in ferromagnets through a spin-transfer torque. We report that antiferromagnets allow two such spin-transfer torques and present a microscopic analysis that interpolates ferro- and antiferromagnetic transport regimes.
-
Exploring the Basic Principles and Functionalities of Spintronic Thermal Management
Magnetic properties in condensed matter
Structure and mechanical and thermal properties in condensed matter
2021-12-13
Scientists propose a new spin caloritronics concept called “spintronic thermal management” and provide a comprehensive overview of basic principles, physical behaviors, and heat control functionalities associated with the concept.
-
The Mysteries of Charge Order and Charge Fluctuations in Cuprate Superconductors
Superconductivity
Dielectric, optical, and other properties in condensed matter
Structure and mechanical and thermal properties in condensed matter
Magnetic properties in condensed matter
2021-11-16
This Special Topics issue condenses the latest research on the enigmatic characteristics of high-temperature superconductivity in cuprates through the observation and elucidation of charge order, charge fluctuations, and other phenomena.
-
Measurements and Implications of Shot Noise in Mesoscopic Systems
Electronic transport in condensed matter
Magnetic properties in condensed matter
Superconductivity
2021-9-29
Shot noise measurements provide rewarding insights into system properties, non-equilibrium phenomena, and quantum effects in mesoscopic systems.