2022 CAP Congress / Congrès de l'ACP 2022

(G*) Inverse Laplace transform of NMR spin-lattice relaxation data

8 Jun 2022, 10:45

15m

MDCL 1010 (McMaster University)

Oral Competition (Graduate Student) / Compétition orale (Étudiant(e) du 2e ou 3e cycle) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) W1-9 Quantum Magnetism (DCMMP) | Magnétisme quantique (DPMCM)

Speaker

Jiaming Wang

Description

Traditional NMR data analysis techniques, such as the stretched exponential fit, are used to determine the sample-averaged nuclear spin-lattice relaxation rate $1/T_1$. However, they face difficulty when dealing with heterogeneous materials with NMR signals coming from distinct local environments, especially those with large, overlapping distributions of their Knight shifts and $1/T_1$.

To overcome this, we perform inverse Laplace transform (ILT) to obtain the histogram $P(1/T_1)$ of the $1/T_1$ distribution from the nuclear spin recovery curve $M(t)$. We apply this technique to ${}^{63}$Cu and ${}^{79}$Br NQR data of kagome lattice materials herbertsmithite (ZnCu${}_3$(OD)${}_6$Cl${}_2$) and Zn-barlowite (ZnCu${}_3$(OD)${}_6$FBr) as well as ${}^{19}$F NMR data of the latter.

From the ${}^{63}$Cu data, we were able to use ILT to observe the gradual emergence of spin singlets with spatially varying excitation gaps below $\sim$30~K in both materials. We also performed ILT across the ${}^{19}$F NMR spectrum to obtain 3-dimensional ILT-resolved NMR lineshapes, which allowed us to separate the signals coming from two distinct, overlapping sites.

[1] J. Wang et al., Nat. Phys. 17, 1109–1113 (2021)

[2] J. Wang, W Yuan et al., Phys. Rev. Lett. (in press)