Determining Curie temperatures in dilute ferromagnetic semiconductors: High Curie temperature (Ga,Mn)As

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. A convenient way of determining the ferromagnetic transition temperature of metallic (Ga,Mn)As

Three-dimensional Heisenberg critical behavior in the highly disordered dilute ferromagnetic semiconductor (Ga,Mn)As

“…This leads to the resistivity having a peak at T C [21]. In dilute ferromagnetic semiconductors such as (Ga,Mn)As [18,22] and ferromagnetic metals [23], the carrier and moment densities are comparable. This leads to the temperature derivative of resistance having a peak at T C , which has the same functional form as that of the specific heat [24].…”

“…At lower |t| (very close to T C ), the Kouvel-Fisher plots are very nonlinear, with a marked drop-off close to T C . These apparent drop-offs and associated apparent increase in the exponent β just below T C are the result of sample inhomogeneity [22]. Taking the observable critical range to be 0.025 > |t| > 0.005 gives β = 0.361 ± 0.005 and 0.373 ± 0.007, respectively, for the 12% and 11% samples.…”

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

“…Ввиду рассеяния носителей заряда на этих флуктуациях на зависимости ρ x x (T ) (см. T c [16], которая для исследуемых образцов состави-ла 19−20 K. Наличие данного пика является первич-ным свидетельством взаимодействия дырок в канале и магнитного слоя. Стоит отметить, что при дальней-шем понижении температуры (ниже 15 K) ρ x x вновь начинает возрастать, что связывается с проявлением квантовых поправок к проводимости, рассматривае-мых далее.…”

Curie temperature of Co-doped TiO2 as functions of carrier density and Co content evaluated from electrical transport and magnetization at low temperature regime

“…It is noted that the local minimum was not always observed in all samples because of the limited temperature range for the transport measurement. The suitable range of carrier density was required to evaluate T C by transport measurement, on the other hand, the magnetization measurement was applicable to all films to evaluate the relationship of T C vs. n. By using the power-law of magnetization for critical region below T C , M r ∝ (1 − T/T C ) β , the KF plot can be applied as (dlnM r /dT) −1 − T curve yielding T C from the intercept of linear fitting on T-axis as previously used in various compounds such as (Ga,Mn)As, 17 LaSrCoO 3 , 21 and (Pr, Sr)MnO 3 . 22 Figure 3 shows temperature dependence of remanent magnetization (M r -T) and its corresponding KF plots for anatase Ti 0.95 Co 0.05 O 2−δ films with different n. The obtained concave M r -T curve suggests the presence of bound magnetic polarons.…”

“…Recently, the Kouvel-Fischer (KF) plot 16 was also used to cross-evaluate T C of (Ga,Mn)As in comparison with that obtained from kink structure. 17 These methods could be applied to evaluate T C of Co-doped TiO 2 by extrapolating from low temperature measurements. In this study, we systematically investigated the T C of anatase Co-doped TiO 2 thin films from electrical transport and magnetization measurements at lower temperatures than T C .…”