Fluctuating magnetic droplets immersed in a sea of quantum spin liquid

Zihao Zhu; Binglin Pan; Linpeng Nie; Jiamin Ni; Yanxing Yang; Changsheng Chen; Chengyu Jiang; Yeyu Huang; Erjian Cheng; Yunjie Yu; Jianjian Miao; Adrian D Hillier; Xianhui Chen; Tao Wu; Yi Zhou; Shiyan Li; Lei Shu

doi:10.1016/j.xinn.2023.100459

Fluctuating magnetic droplets immersed in a sea of quantum spin liquid

Innovation (Camb). 2023 Jun 14;4(5):100459. doi: 10.1016/j.xinn.2023.100459. eCollection 2023 Sep 11.

Authors

Zihao Zhu¹, Binglin Pan¹, Linpeng Nie², Jiamin Ni¹, Yanxing Yang¹, Changsheng Chen¹, Chengyu Jiang¹, Yeyu Huang¹, Erjian Cheng¹, Yunjie Yu¹, Jianjian Miao³, Adrian D Hillier⁴, Xianhui Chen^{2

5

6}, Tao Wu^{2

5

6}, Yi Zhou^{7

8

9}, Shiyan Li^{1

5

10}, Lei Shu^{1

5

10}

Affiliations

¹ State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China.
² CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
³ Department of Physics, the University of Hong Kong, Hong Kong, China.
⁴ ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK.
⁵ Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
⁶ CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, China.
⁷ Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China.
⁸ Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.
⁹ Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China.
¹⁰ Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.

Abstract

The search of quantum spin liquid (QSL), an exotic magnetic state with strongly fluctuating and highly entangled spins down to zero temperature, is a main theme in current condensed matter physics. However, there is no smoking gun evidence for deconfined spinons in any QSL candidate so far. The disorders and competing exchange interactions may prevent the formation of an ideal QSL state on frustrated spin lattices. Here we report comprehensive and systematic measurements of the magnetic susceptibility, ultralow-temperature specific heat, muon spin relaxation (μSR), nuclear magnetic resonance (NMR), and thermal conductivity for NaYbSe₂ single crystals, in which Yb³⁺ ions with effective spin-1/2 form a perfect triangular lattice. All these complementary techniques find no evidence of long-range magnetic order down to their respective base temperatures. Instead, specific heat, μSR, and NMR measurements suggest the coexistence of quasi-static and dynamic spins in NaYbSe₂. The scattering from these quasi-static spins may cause the absence of magnetic thermal conductivity. Thus, we propose a scenario of fluctuating ferrimagnetic droplets immersed in a sea of QSL. This may be quite common on the way pursuing an ideal QSL, and provides a brand new platform to study how a QSL state survives impurities and coexists with other magnetically ordered states.

Keywords: muon spin relaxation; nuclear magnetic resonance; quantum spin liquid; thermal conductivity.