Title: Slow spin dynamics in the hyperhoneycomb lattice [ ( C 2 H 5 ) 3 NH ] 2 Cu 2 ( C 2 O 4 ) 3 revealed by H 1 NMR studies

Abstract

We report the results of magnetic susceptibility $\chi$ and ${}_1\mathrm{H}$ nuclear magnetic resonance (NMR) measurements on a three-dimensional hyperhoneycomb lattice compound $\left[\right({\mathrm{C}}_2{\mathrm{H}}_5{)}_3\mathrm{NH}{]}_2{\mathrm{Cu}}_2{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3$ (CCCO). The average value of the antiferromagnetic (AFM) exchange coupling between the ${\mathrm{Cu}}^{2+}$ $(S=1/2)$ spins was determined to be $J~50$ K from the $\chi$ measurements. No long-range magnetic ordering has been observed down to $T=50$ mK, although NMR lines become slightly broader at low temperatures below 1 K. The broadening of the NMR spectrum observed below 1 K reveals that the Cu spin moments remain at this temperature, suggesting a non-spin-singlet ground state. The temperature and magnetic field dependence of $1/T_1$ at temperatures above 20 K is well explained by paramagnetic thermal spin fluctuations where the fluctuation frequency of ${\mathrm{Cu}}^{2+}$ spins is higher than the NMR frequency of the order of megahertz. However, a clear signature of the slowing down of the ${\mathrm{Cu}}^{2+}$ spin fluctuations was observed at low temperatures where $1/T_1$ shows a thermally activated behavior. The magnetic field dependence of the magnitude of the spin excitation gap suggests that the magnetic behaviors of CCCO are characterized as an AFM chain at low temperatures.

Authors:

Ding, Q.-P.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-7488-066X"

Dissanayake, C. ^[2]; Pakhira, Santanu ^[1]; Newsome, W. J. ^[2]; Uribe-Romo, F. ^[2]; Johnston, D. C.  ^[1];

• Search DOE PAGES for author "Johnston, D. C."
• Search DOE PAGES for ORCID "0000-0001-6639-1831"

Nakajima, Y.  ^[2];

• Search DOE PAGES for author "Nakajima, Y."
• Search DOE PAGES for ORCID "0000-0002-4584-3621"

Furukawa, Y.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-3722-293X"

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+ Show Author Affiliations

1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
2. Univ. of Central Florida, Orlando, FL (United States)

Publication Date:

Thu Mar 10 00:00:00 EST 2022

Research Org.:

Ames Laboratory (AMES), Ames, IA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Science Foundation (NSF)

OSTI Identifier:

1864158

Report Number(s):

IS-J 10,767
Journal ID: ISSN 2469-9950; DMR-1944975; TRN: US2305685

Grant/Contract Number:  

AC02-07CH11358; DMR-1944975

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review. B

Additional Journal Information:

Journal Volume: 105; Journal Issue: 10; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; frustrated magnetism; quantum spin liquid; spin dynamics; 1-dimensional systems; 3-dimensional systems; nuclear magnetic resonance