2009年11月
Tilted-Cone-Induced Easy-Plane Pseudo-Spin Ferromagnet and Kosterlitz-Thouless Transition in Massless Dirac Fermions
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
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- 巻
- 78
- 号
- 11
- 開始ページ
- 11471-1-11471-7
- 終了ページ
- 記述言語
- 英語
- 掲載種別
- DOI
- 10.1143/JPSJ.78.114711
- 出版者・発行元
- PHYSICAL SOC JAPAN
The possible quantum Hall ferromagnet at a filling factor v = 0 is investigated for the zero-energy (N = 0) Landau level of the two dimensional massless Dirac fermions in alpha-(BEDT-TTF)(2)I-3 under pressure with tilted cones and a twofold valley degeneracy resulting from time-reversal symmetry. In the case of the Dirac cones without tilting, the long-range Coulomb interaction in the N = 0 Landau level exhibits the SU(2) valley-pseudo-spin symmetry even to the order O(a/l(H)), in contrast to N not equal 0 Landau levels, where a and l(H) represent the lattice constant and the magnetic length, respectively. Such a characteristic comes from a fact that zero-energy states in a particular valley are restricted to only one of the spinor components, whereas the other spinor component is necessarily zero. In the case of the tilted Dirac cones as found in alpha-(BEDT-TTF)(2)I-3, one obtains a non-zero value of the second component and then the backscattering processes between valleys becomes non-zero. It is shown that this fact can lead to easy-plane pseudospin ferromagnetism (XY-type). In this case, the phase fluctuations of the order parameters can be described by the XY model leading to Kosterlitz-Thouless transition at lower temperature. In view of these theoretical results, experimental findings in resistivity of alpha-(BEDT-TTF)(2)I-3 are discussed.
- リンク情報
- ID情報
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- DOI : 10.1143/JPSJ.78.114711
- ISSN : 0031-9015
- Web of Science ID : WOS:000272060900037