Criticality-Enhanced Magnetocaloric Effect in Quantum Spin Chain Material Copper Nitrate
Date
2017-03-15
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Nature Publishing Group
Abstract
In this work, a systematic study of Cu(NO3)2·2.5 H2O (copper nitrate hemipentahydrate, CN), an
alternating Heisenberg antiferromagnetic chain model material, is performed with multi-technique
approach including thermal tensor network (TTN) simulations, first-principles calculations, as well
as magnetization measurements. Employing a cutting-edge TTN method developed in the present
work, we verify the couplings J = 5.13 K, α = 0.23(1) and Landé factors g∥= 2.31, g⊥ = 2.14 in CN,
with which the magnetothermal properties have been fitted strikingly well. Based on first-principles
calculations, we reveal explicitly the spin chain scenario in CN by displaying the calculated electron
density distributions, from which the distinct superexchange paths are visualized. On top of that,
we investigated the magnetocaloric effect (MCE) in CN by calculating its isentropes and magnetic
Grüneisen parameter. Prominent quantum criticality-enhanced MCE was uncovered near both critical
fields of intermediate strengths as 2.87 and 4.08 T, respectively. We propose that CN is potentially a very
promising quantum critical coolant.
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Citation
Xiang, J.-S. et al. Criticality-Enhanced Magnetocaloric Effect in Quantum Spin Chain Material Copper Nitrate. Sci. Rep. 7, 44643; doi: 10.1038/srep44643 (2017).