Journal Article FZJ-2015-07122

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Low-lying magnetic excitations and magnetocaloric effect of molecular magnet K $_{6}$ [V $_{15}$ As $_{6}$ O $_{42}$ (H $_{2}$ O)] · 8H $_{2}$ O

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2015
EDP Science65224 Les-Ulis

epl 112(2), 27003 () [10.1209/0295-5075/112/27003]

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Abstract: Low-temperature heat capacity measurements were performed on the molecular nanomagnet $\text{K}_{6}[\text{V}_{15}\text{As}_{6}\text{O}_{42}(\text{H}_{2}\text{O})] \cdot8\text{H}_{2}{\text{O}}$ (V15). The low-lying magnetic excitations are clearly evidenced by the Schottky anomalies in the specific-heat data. The energy levels determined from the low-temperature observables agree well with the three-spin model for V15. The magnetocaloric effect of V15 is examined. The maximum entropy change of $5.31\ \text{Jkg}^{-1}\text{K}^{-1}$ is found for a field change of $\Delta H =(8-0.5)\ \text{T}$ at ${\sim}1.5\ \text{K}$ . In spite of the low ground-state spin of V15, a drastic entropy change of $4.12\ \text{Jkg}^{-1}\text{K}^{-1}$ is observed for a field change of $\Delta H = (8-0.05)\ \text{T}$ at 0.4 K, which is comparable to the entropy change of some high-spin sub-kelvin magnetic coolers at such low temperatures. Anisotropy and consequent zero-field splitting result in this characteristic of V15 and may open new possibilities in the design of ultra-low-temperature molecular coolers.

Keyword(s): Information and Communication (1st) ; Condensed Matter Physics (2nd)

Classification:

Contributing Institute(s):
  1. JCNS-FRM-II (JCNS-FRM-II)
  2. Streumethoden (JCNS-2)
  3. Streumethoden (PGI-4)
  4. Elektronische Eigenschaften (PGI-6)
Research Program(s):
  1. 524 - Controlling Collective States (POF3-524) (POF3-524)
  2. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
  3. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
  4. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)
Experiment(s):
  1. No specific instrument

Appears in the scientific report 2015
Database coverage:
Medline ; OpenAccess ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection
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Institute Collections > JCNS > JCNS-FRM-II
Document types > Articles > Journal Article
Institute Collections > JCNS > JCNS-2
Institute Collections > PGI > PGI-6
Institute Collections > PGI > PGI-4
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 Record created 2015-12-04, last modified 2025-01-29