Europhys. Lett.
Volume 60, Number 2, October 2002
Page(s) 276 - 280
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 October 2002
DOI: 10.1209/epl/i2002-00347-0

Europhys. Lett., 60 (2) , pp. 276-280 (2002)

Quantum phase transition in the dioptase magnetic lattice

C. Gros1, P. Lemmens2, K.-Y. Choi3, G. Güntherodt3, M. Baenitz4 and H. H. Otto5

1  Fachbereich Physik, Postfach 151150, Universität des Saarlandes 66041 Saarbrücken, Germany
2  IMNF, TU Braunschweig, D-38106 Braunschweig, Germany
3  II. Physikalisches Institut, RWTH-Aachen Templergraben 55, 52056 Aachen, Germany
4  Max-Planck-Institut für Chemische Physik fester Stoffe MPI-CPfS, D-01187 Dresden, Germany
5  Institut für Mineralogie und Mineralische Rohstoffe, TU Clausthal D-38678 Clausthal-Zellerfeld, Germany

(Received 17 April 2002; accepted in final form 6 August 2002)

The study of quantum phase transitions (see Sachdev S., Quantum Phase Transitions (Cambridge University Press, Cambridge) 1999), which are zero-temperature phase transitions between distinct states of matter, is of current interest in research since it allows for a description of low-temperature properties based on universal relations. Here we show that the crystal green dioptase $\chem{Cu_{6}Si_{6}O_{18}\cdot 6H_2O}$, known to the ancient Romans as the gem of Venus, has a magnetic crystal structure, formed by the Cu(II) ions, which allows for a quantum phase transition between an antiferromagnetically ordered state and a quantum spin liquid.

71.20.Be - Transition metals and alloys.
73.43.Nq - Quantum phase transitions.
75.10.Jm - Quantized spin models.

© EDP Sciences 2002