Specific Heat Study on a Novel Spin-Gapped System : (CH_3)_2NH_2CuCl_3

Abstract

Specific heat measurements down to 120mK have been performed on a quasi-one-dimensional $S=1/2$ spin-gapped system (CH${}_3$)${}_2$NH${}_2$CuCl${}_3$ in a magnetic field up to 8 T. This compound has a characteristic magnetization curve which shows a gapless ground state and a plateau at 1/2 of the saturation value. We have observed a spontaneous antiferromagnetic ordering and a field-induced one below and above the 1/2 plateau field range, respectively. The field versus temperature phase diagram is quite unusual and completely different from those of the other quantum spin systems investigated so far. In the plateau field range, a double-structure in the specific heat is observed, reflecting the coexistence of ferromagnetic and antiferromagnetic excitations. These behaviors are discussed on the basis of a recently proposed novel quantum spin chain model consisting of weakly coupled ferromagnetic and antiferromagnetic dimers.

4 pages, 3 figures, submitted to J. Phys. Soc. Jpn

References in corpus (7)

• Realization of Bose-Einstein condensation of dilute magnons in TlCuCl${}_3$
• Field-Induced Magnetic Ordering in the Quantum Spin System KCuCl${}_3$
• Low Temperature Properties of Quantum Antiferromagnetic Chains with Alternating Spins S=1 and 1/2
• Thermodynamic Properties of Heisenberg Ferrimagnetic Spin Chains: Ferromagnetic-Antiferromagnetic Crossover
• Thermodynamics of the (1,1/2) Ferrimagnet in Finite Magnetic Fields
• High-field phase diagram of the Haldane-gap antiferromagnet $Ni(C_5{H}_{14}{N}_2{)}_2{N}_3(P{F}_6)$
• Specific Heat Study of an S=1/2 Alternating Heisenberg Chain System F_5PNN Under Magnetic Field

Cited by in corpus (3)

• Spin Liquids and Antiferromagnetic Order in the Shastry-Sutherland-Lattice Yb${}_2$Pt${}_2$Pb
• Heat transport of the quasi-one-dimensional alternating spin chain material (CH_{3})_{2}NH_{2}CuCl_{3}
• Combined analytical and numerical approach to magnetization plateaux in one-dimensional spin tube antiferromagnets