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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 3 Issue 3 (1998) pp 341-347
Quantum fluctuations and ground state of weakly interacting helix spin chains in a magnetic field
E. Rastelli (a), A. Tassi
Dipartimento di Fisica dell' Università and Istituto Nazionale per la Fisica della Materia Via delle Scienze, 43100 Parma, Italy
Received: 9 September 1997 / Revised: 15 October 1997 / Accepted: 17 November 1997
Abstract: Ferromagnetic spin chains of a hexagonal lattice coupled by a weak antiferromagnetic interaction J1 develop a helix arrangement if the intrachain antiferromagnetic NNN exchange J2 is sufficiently large. We show that the classical minimum energy spin configuration is an umbrella when an external magnetic field is applied. The scenario is dramatically changed by quantum fluctuations. Indeed we find that the zero point motion forces the spins in a plane containing the magnetic field so that classical expectation is deceptive for our model. Our result is obtained by controlled expansion in the low field-long wavelength modulation limit.
PACS. 75.10.Jm Quantized spin models - 75.30.Ds Spin waves - 75.50.-y Studies of specific magnetic materials
(a) email: rastelli@fisica.unipr.it
Article in PDF-Format (329 KB)
Online publication: July 14, 1998
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