广东省磁电物性分析与器件重点实验室学术讲座（第八十七期）

报告人:

Prof.Devashibhai Adroja（Rutherford Appleton Laboratory, ISIS facility）

题目: 

Quantum critical spin-liquid in geometrically frustrated Kagome lattice probed by μSR and neutron scattering

利用μSR与中子散射探测笼目晶格中的量子临界自旋液体

地点：

Bodog会员尊享平台南校园550栋二楼报告厅

时间:

2026年6月26日（星期五）上午10:00

主持人：

谢涛 副教授

报告简介：

Kagome-lattice Kondo systems are of considerable interest because they combine geometric frustration with Kondo interactions between localized moments and itinerant electrons. This interplay can stabilize unconventional magnetic states, heavy-fermion behaviour, quantum criticality, and potentially topological phases. As a result, these materials provide an important platform for studying emergent quantum phenomena arising from competing interactions in strongly correlated electron systems. The valence fluctuating heavy-fermion compound CeRhSn is a particularly intriguing example, where strong Kondo interactions and geometrical frustration suppress long-range magnetic order. Here, we present the results of muon spin relaxation (μSR) and neutron scattering on the Ce-based quasikagome lattice CeRh1−xPdxSn (x = 0.1 to 0.75). Zero-field (ZF) μSR results reveal the absence of both static long-range magnetic order and spin freezing down to 0.05 K in the single-crystal sample of x = 0.1, while the longitudinal-field (LF) dependence indicate the presence of dynamic spin fluctuations persisting even at T = 0.05 K without static magnetic order. On the other hand, the magnetic specific heat divided by temperature C4f/T increases as −logT on cooling below 0.9 K, passes through a broad maximum at 0.13 K, and slightly decreases on further cooling. The ac-susceptibility also exhibits a frequency-independent broad peak at 0.16 K, which is prominent with an applied field H along the c direction. We, therefore, argue that such a behaviour for x = 0.1 can be attributed to a metallic spin-liquid-like ground state near the quantum critical point in the frustrated Kondo lattice. The LF-μSR study suggests that the out of kagome plane spin fluctuations are responsible for the spin-liquid (SL) behaviour. Low-energy inelastic neutron scattering (INS) of x = 0.1 reveals gapless magnetic excitations, which are also supported by the behaviour of C4f proportional to T1.1 down to 0.06 K. The ZF-μSR results for the x = 0.2 polycrystalline sample exhibit similar behaviour to that of x = 0. The ZF-μSR results for the x = 0.5 sample are interpreted as a possible long-range antiferromagnetic (AFM) ground state below TN = 0.8 K. However, neutron diffraction detects substantial magnetic diffuse scattering at 0.1 K, highlighting the persistence of frustration within the kagome Ce sublattice. These results establish CeRh1-xPdxSn as a model frustrated Kondo-lattice system that hosts a crossover from a metallic spin-liquid-like state to long-range magnetic order with increasing Pd concentration.

报告人简介：

Prof. Devashibhai Adroja is a senior scientist and STFC Fellow at the Rutherford Appleton Laboratory, ISIS facility and is responsible for the MERLIN spectrometer and visiting Professor at Johannesburg University. He is an acknowledged expert in the magnetism of d- and f-electron systems and has more than 35 years of experience in inelastic neutron scattering, neutron diffraction, X-ray scattering and muon spin rotation techniques. His research programme focuses on strongly correlated electron systems, with special emphasis on quantum criticality and non-Fermi-liquid behaviour, heavy Fermions, unconventional superconductivity, quantum spin liquid in transition-metal and rare earth oxides, manganites and thermoelectric materials. He works on the frontiers of condensed matter physics and has recently made significant contributions on the quantum spin-liquid materials, quasi-1D spin-chain systems, double/triple/quadruple perovskites, Honeycomb ruthenates, Fe and Ni-superconductors and heavy fermion materials. He has published over 450 papers in peer-reviewed international journals and given 106 invited talks/seminars internationally. His h-index is of51 and an i10-index of 239, with a total of 11123 citations. He was awarded the prestigious invitation fellowship from the Japanese Society for the Promotion of Science (JSPS) in 2016 and Advanced Newton Fellowship funding between UK-China from the Royal Society of London in 2020-2024, International Exchanges 2020 Cost Share (JSPS) funding from the Royal Society of London in 2020-2024, EPSRC-UK funding grant in 2022-2026 and PIFI Fellowship (China). He has provided training to several post-doctoral fellows and co-supervised Ph.D. students and Master students. His international reputation is reflected as a member of beam time review panels at J-PARC (Japan), and ANSTO (Australia), as well as a member of the steering committee of Indian Nanomission-RAL programme on neutron and muon facility. He has more than 40 fruitful experimental and theoretical collaborations groups, both nationally and internationally.