Title: Geometric Frustration on the Trillium Lattice in a Magnetic Metal-Organic Framework

Abstract

In the dense metal-organic framework $\mathrm{Na}\left[\mathrm{Mn}{\left(\mathrm{HCOO}\right)}_3\right]$, ${\mathrm{Mn}}^{2+}$ ions ( $S=\frac{5}{2}$) occupy the nodes of a “trillium” net. In this work, we show that the system is strongly magnetically frustrated: the Néel transition is suppressed well below the characteristic magnetic interaction strength; short-range magnetic order persists far above the Néel temperature; and the magnetic susceptibility exhibits a pseudo-plateau at $\frac{1}{3}$-saturation magnetization. A simple model of nearest-neighbor Heisenberg antiferromagnetic and dipolar interactions accounts quantitatively for all observations, including an unusual 2- $\mathbf{k}$ magnetic ground state. We show that the relative strength of dipolar interactions is crucial to selecting this particular ground state. Geometric frustration within the classical spin liquid regime gives rise to a large magnetocaloric response at low applied fields that is degraded in powder samples as a consequence of the anisotropy of dipolar interactions.

Authors:

Bulled, Johnathan M.  ^[1];

• Search DOE PAGES for author "Bulled, Johnathan M."
• Search DOE PAGES for ORCID "0000-0001-5017-0313"

Paddison, Joseph A. M. ^[2]; Wildes, Andrew  ^[3];

• Search DOE PAGES for author "Wildes, Andrew"
• Search DOE PAGES for ORCID "0000-0003-3957-2818"

Lhotel, Elsa ^[4]; Cassidy, Simon J. ^[1]; Pato-Doldán, Breogán  ^[5];

• Search DOE PAGES for author "Pato-Doldán, Breogán"
• Search DOE PAGES for ORCID "0000-0003-2302-8623"

Gómez-Aguirre, L. Claudia  ^[6];

• Search DOE PAGES for author "Gómez-Aguirre, L. Claudia"
• Search DOE PAGES for ORCID "0000-0001-8822-0910"

Saines, Paul J.  ^[7];

• Search DOE PAGES for author "Saines, Paul J."
• Search DOE PAGES for ORCID "0000-0002-4207-2112"

Goodwin, Andrew L. ^[1]

---

+ Show Author Affiliations

1. Univ. of Oxford (United Kingdom). Inorganic Chemistry Lab.
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Cambridge (United Kingdom)
3. Inst. Laue-Langevin (ILL), Grenoble (France)
4. Institut Néel, Grenoble (France)
5. Univ. of Bergen (Norway)
6. University of A Coruña (Spain)
7. Univ. of Kent, Canterbury (United Kingdom)

Publication Date:

Tue Apr 26 00:00:00 EDT 2022

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); European Research Council (ERC); Engineering and Physical Sciences Research Council (EPSRC); Leverhulme Trust; European Union Horizon 2020

OSTI Identifier:

1869123

Grant/Contract Number:  

AC05-00OR22725; 788144; EP/T027886/1; RPG-2018-268; 824109

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Letters

Additional Journal Information:

Journal Volume: 128; Journal Issue: 17; Journal ID: ISSN 0031-9007

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; frustrated magnetism; magnetocaloric effect; crystal structures; inorganic compounds; magnetization measurements; Monte Carlo methods; neutron diffraction