Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2005-12-21
Physics
Condensed Matter
Strongly Correlated Electrons
Accepted for publication in Physical Review B. 22 pages, 7 figures
Scientific paper
10.1103/PhysRevB.73.024411
We calculate Curie temperatures and study the stability of ferromagnetism in diluted magnetic materials, taking as a model for the exchange between magnetic impurities a damped Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and a shor t range term representing the effects of superexchange. To properly include effects of spin and thermal fluctuations as well as geometric disorder, we solve the effective Heisenberg Hamiltonian by means of a recently developed semi-analytical approach. This approach, ``self-consistent local Random Phase Approximation (SC-L RPA)'', is explained. We show that previous mean-field treatments, which have been widely used in the literature, largely overestimate both the Curie temperatures and the stability of ferromagnetism as a function of carrier density. The discr epancy when compared to the current approach was that effects of frustration in RKKY oscillations had been strongly underestimated by such simple mea n-field theories. We argue that the use, as is frequent, of a weakly-disordered RKKY exchange to model ferromagnetism in diluted III-V systems is inconsistent with the observation of ferromagnetism over a wide region of itinerant carrier densities. This may be puzzling when compared to the apparent success of calculations based on {\it ab-initio} estimates of the coupling; we propose a resolution to this issue by taking RKKY-like interactions between resonant states close to the Fermi level.
Bouzerar Richard
Ziman Timothy
~Bouzerar Georges
No associations
LandOfFree
Why RKKY exchange integrals are inappropriate to describe ferromagnetism in diluted magnetic semiconductors does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Why RKKY exchange integrals are inappropriate to describe ferromagnetism in diluted magnetic semiconductors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Why RKKY exchange integrals are inappropriate to describe ferromagnetism in diluted magnetic semiconductors will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-421852