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Dimensional crossover in strongly anisotropic antiferromagnets

English title Dimensional crossover in strongly anisotropic antiferromagnets
Applicant Mudry Christopher
Number 116635
Funding scheme Project funding
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Theoretical Physics
Start/End 01.05.2007 - 30.04.2010
Approved amount 141'974.00
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All Disciplines (2)

Theoretical Physics
Condensed Matter Physics

Keywords (4)

strongly correlated electronic systems; strongly correlated system; quantum magnetism; quantum criticality

Lay Summary (English)

Lay summary
Magnetic materials are very often characterized by anisotropic magnetic interactions both in the internal space of the spin and on the lattice.
This project is primarily concerned with quantum antiferromagnets that have strongly anisotropic magnetic interactions on the lattice.
At temperatures much larger than the
characteristic subleading magnetic interaction J', magnetic fluctuations are predominantly two- or one-dimensional if the characteristic dominant antiferromagnetic coupling J is an intraplane or an intrachain coupling, respectively.
Upon decreasing temperature,
magnetic fluctuations become more isotropic and, under suitable conditions, magnetic long-range order can appear below the critical temperature T_{AF}(J'/J).
The random phase approximation (RPA) has been a popular approximation to estimate the ordering temperature T_{AF}(J'/J) in the strong anisotropic limit J'<<$.

Recently, the quality of this approximation has been tested by the use of Monte Carlo simulations for the quasi-two-dimensional quantum antiferromagnetic spin-S Heisenberg model on the cubic lattice.
Remarkably, it was shown by
Yasuda \textit{et al}.,
Phys. Rev. Lett. 94, 217201 (2005),
that the coordination number,
a number of geometrical origin that enters the RPA approximation, is simply renormalized by an amount independent of the spin quantum number S in the limit J'/J->0.
An explanation for this property was given by Hastings and Mudry, Phys. Rev. Lett. 96, 027215 (2006), who argued for the existence of three universal scaling functions of one scaling variable in the limit J'/J->0 and at the ordering temperature.
All three functions can be measured by neutron scattering.

This project aims at improving over the RPA in the following contexts.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
129928 Dimensional crossover in strongly anisotropic antiferromagnets 01.05.2010 Project funding
129928 Dimensional crossover in strongly anisotropic antiferromagnets 01.05.2010 Project funding