2022 CAP Congress / Congrès de l'ACP 2022

(I) Nuclear Magnetic Resonance as a Local Probe of the Disordered Ground State of Proximate Quantum Spin Liquid Materials

7 Jun 2022, 14:15

30m

MDCL 1309 (McMaster University)

Invited Speaker / Conférencier(ère) invité(e) Symposia Day (DCMMP) - Fluctuations and Disorder in Condensed Matter T3-7 Fluctuations and Disorder in Condensed Matter (DCMMP) | Fluctuations et désordre en matière condensée (DPMCM)

Speaker

Takashi Imai (McMaster University)

Description

Understanding the nature of the quantum spin liquids (QSL) is the holy grail of quantum condensed matter physics with a broad range of implications to other research fields. Many materials, such as the kagome lattice Heisenberg antiferromagnet (KLHA) consisting of Cu${}^{2+}$ ions with spin S=1/2 arranged in a corner sharing triangle geometry, have been proposed as the model system for the QSL. However, they all suffer from various complications, such as the phase transition into the long-range ordered ground state (which should not take place in the real QSL). The few materials that do not undergo a long-range order tend to have structural disorder. Recent research indicated that structural disorder often affects the properties of the proximate QSL materials in a profound manner, making the interpretation of the experimental findings non-trivial. Nuclear magnetic resonance is a local probe, and in principle suited for characterizing the disorder effects in materials. In practice, the distribution of the NMR spin-lattice relaxation rate $1/T_1$ induced by disorder prevented proper data interpretation for decades. In this talk, we will explain how one can deduce the distribution function $P(1/T_1)$ of $1/T_1$ based on inverse Laplace transform (ILT) of the nuclear magnetization recovery [1]. $P(1/T_1)$ provides rich information, such as the fraction of spin singlets in the KLHA [2].

[1] P.M. Singer et al., Phys. Rev. B 101, 174508 (2020).
[2] J. Wang, W. Yuan et al., Nature Physics 17, 1109-1113 (2021). DOI: 10.1038/s41567-021-01310-3