Magnetocaloric Effect in a Frustrated Gd-Garnet with No Long-Range Magnetic Order
Journal Article
·
· Inorganic Chemistry
- Technische Univ. Wien (Austria)
- Univ. of Texas at El Paso, TX (United States)
- Texas A & M Univ., College Station, TX (United States)
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Univ. of Zagreb (Croatia)
- New Mexico State Univ., Las Cruces, NM (United States)
In this work, the hyperkagome lattice of Gd spins in a garnet compound, Gd3CrGa4O12, is studied using bulk measurements and density functional computations, and the observation of large magnetocaloric effect corresponding to an entropy change, ΔSm = 45 Jkg-1K-1 (≈ 45 J mol-1K-1) at 2 K, 8 T is reported. Though the compound defies long-range magnetic order down to 0.4 K, a broad feature below 10 K is observed in the specific heat with two low temperature anomalies at T* ≈ 0.7 K and TS ≈ 2.45 K. The anomaly at T* is reminiscent of one in Gd3Ga5O12, where it is related to the development of a complex magnetic phase, whereas the TS-peak is accounted for by a multilevel Schottky-like model. The spin-lattice relaxation times studied by nuclear magnetic resonance experiments show that the relaxation is dominated by the magnetic fluctuations in Cr which has a longer relaxation time compared to that of the garnet, Lu3CrGa4O12 containing a nonmagnetic rare earth. Our first-principles density functional theory calculations agree well with the experimental results and support short-range magnetic order in the Gd-sublattice and antiferromagnetism in the Cr-sublattice. The importance of spin fluctuations and short-range order in the rare earth and transition metal lattices in garnets resulting in large magnetocaloric effect is brought out through this work.
- Research Organization:
- Idaho National Laboratory (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- Croatian Science Foundation; European Regional Development Fund; Extreme Science and Engineering Discovery Environment (XSEDE); Robert A. Welch Foundation; Swiss National Science Foundation (SNSF); USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
- Grant/Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1687369
- Alternate ID(s):
- OSTI ID: 1759037
- Report Number(s):
- INL/JOU--19-56395-Rev000
- Journal Information:
- Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 20 Vol. 59; ISSN 0020-1669
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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