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Drastic Change of Magnetic Phase Diagram in Doped Quantum Antiferromagnet TlCu$_{1-x}$Mg$_x$Cl$_3$

M. Fujisawa·T. Ono·H. Fujiwara·H. Tanaka·V. Sikolenko·M. Meissner·P. Smeibidl·S. Gerischer·H. A. Graf
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Abstract

TlCuCl$_3$ is a coupled spin dimer system, which has a singlet ground state with an excitation gap of $Δ/gμ_{\mathrm B}$ = 5.5 T. TlCu$_{1-x}$Mg$_x$Cl$_3$ doped with nonmagnetic Mg$^{2+}$ ions undergoes impurity-induced magnetic ordering. Because triplet excitation with a finite gap still remains, this doped system can also undergo magnetic-field-induced magnetic ordering. By specific heat measurements and neutron scattering experiments under a magnetic field, we investigated the phase diagram in TlCu$_{1-x}$Mg$_x$Cl$_3$ with $x\sim 0.01$, and found that impurity- and field-induced ordered phases are the same. The gapped spin liquid state observed in pure TlCuCl$_3$ is completely wiped out by the small amount of doping.

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M. Fujisawa, T. Ono, H. Fujiwara, H. Tanaka, V. Sikolenko, M. Meissner, P. Smeibidl, S. Gerischer, H. A. Graf. 2006-01-18. Drastic Change of Magnetic Phase Diagram in Doped Quantum Antiferromagnet TlCu$_{1-x}$Mg$_x$Cl$_3$. https://doi.org/10.1143/jpsj.75.033702

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