Volume 95, Number 4, August 2011
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||25 July 2011|
Microscopic model for the semiconductor-to-ferromagnetic-metal transition in FeSi1−xGex Alloys
Institut für Theoretische Physik, ETH Zürich - CH-8093 Zürich, Switzerland
2 College of Engineering, Nihon University - Koriyama 963-8642, Japan
3 Max Planck Institut für Physik komplexer Systeme - Nöthnitzer Str. 38, D-01187 Dresden, Germany, EU
Accepted: 25 June 2011
The simplified band structure introduced by Mazurenko et al. to model FeSi is used to analyze the singlet semiconductor to ferromagnetic metal transition in the isoelectronic isostructural alloys, FeSi1−xGex. The complex band structure of the alloy is replaced by an alternating chain of doubly and singly degenerate atoms to represent Fe and Si/Ge, respectively. The former (latter) form narrow (broad) bands with a substantial hybridization between them. A substantial onsite repulsion including Hund's rule coupling is introduced on the Fe sites. The mean-field phase diagram contains a first-order phase transition from the singlet semiconductor to a ferromagnetic metal with increasing temperature and interaction strength, similar to the alloys. The analysis also reproduces the rapid rise of the spin susceptibility in the semiconductor with a crossover to a Curie-Weiss form at higher temperatures. Good agreement is found at zero temperature between the mean-field and accurate DMRG calculations.
PACS: 71.20.Be – Transition metals and alloys / 71.30.+h – Metal-insulator transitions and other electronic transitions / 75.50.Bb – Fe and its alloys
© EPLA, 2011
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.