Weak Localization in Ferromagnetic (Ga,Mn)As Nanostructures

Abstract

We report on the observation of weak localization in arrays of (Ga,Mn)As nanowires at millikelvin temperatures. The corresponding phase coherence length L φ is typically between 100 nm and 200 nm at 20 mK. Strong spin-orbit interaction in the material is manifested by a weak anti-localization correction around zero magnetic field.PACS numbers: 73.43. Jn, 72.25.Dc, 73.43.Qt Quantum corrections to the resistance like weak localization are suppressed by a sufficiently strong perpendicular magnetic field B [1]. Hence the question arises whether such effects can be observed in ferromagnets which have an intrinsic magnetic induction. While few experimental works explored this problem [2,3], a definite experimental answer is still lacking. Hence, the advent of the new ferromagnetic semiconductor material (Ga,Mn)As with significantly smaller internal field compared to conventional ferromagnets offers a new opportunity to address such questions. Ferromagnetic semiconductors like (Ga,Mn)As [4] are interesting materials for spintronics as well, as they combine ferromagnetic properties with the versatility of semiconductors [5]. The spin 5 2 -Mn-ions on regular sites of the zinc-blende lattice of the GaAs host act as acceptors thus providing both holes and magnetic moments. The ferromagnetic order between the Mn-ions is mediated by these holes [6]. By now ferromagnetism in (Ga,Mn)As is well understood, allowing to predict Curie temperatures [6], magnetocrystalline anisotropies [7] as well as the anisotropic magnetoresistance effect [8]. In this respect (Ga,Mn)As is one of the best understood ferromagnetic materials at all [9] and hence suitable as a model system to study quantum corrections to the conductivity.

Weak localization of bulk channels in topological insulator thin films

“…(2.5) are mutually time-reversal partners, the crossover here does not break time-reversal symmetry, different from those in the ferromagnetic semiconductors with spin-orbit coupling 55,56 and magneticallydoped topological surface states. 13,18 B.…”

Weak antilocalization in HgTe quantum wells and topological surface states: Massive versus massless Dirac fermions

“…Refs. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. Such a situation can occur if the two graphene's valleys are coupled by scattering off atomically sharp defects.…”

Квантовые поправки к проводимости и аномальный эффект Холла в квантовых ямах InGaAs с пространственно отделенной примесью Mn

“…Однако, в отличие от ФМ металлов, система (Ga, Mn)As за счет сравнительно малой концентрации магнитных атомов является слабым ФМ. С одной сто-роны, это позволяет более подробно исследовать в ней особенности перехода " металл−диэлектрик", а с другой -наличие слабой спиновой поляризации приво-дит к неоднозначной интерпретации экспериментальных данных [10][11][12].…”

“…Как уже говорилось ранее, в ФМ системах эффект антилокализации должен быть подавлен, хотя в рассматриваемых структурах взаимодействие магнитной и проводящей подсистем достаточно слабое. Отсутствие эффекта антилокализации помогло избежать противоре-чий в интерпретации результатов, которые отмечались в ряде работ [10][11][12].…”