Structural and magnetic properties of the group III-V diluted magnetic semiconductor In1−xMnxSb with x = 0.005–0.06, including the nuclear magnetic resonance (NMR) investigations, are reported. Polycrystalline In1−xMnxSb samples were prepared by direct alloying of indium antimonide, manganese and antimony, followed by a fast cooling of the melt with a rate of 10–12 K/s. According to the X-ray diffraction data, part of Mn is substituted for In, forming the In1−xMnxSb matrix. Atomic force microscopy and scanning tunneling microscopy investigations provide evidence for the presence of microcrystalline MnSb inclusions (precipitates), having a size of ∼100–600 nm, and the fine structure of nanosize grains with a Gaussian distribution around the diameter of ∼24 nm. According to the NMR spectra, the majority of Mn enters the MnSb inclusions. In addition to the single Mn ions, which contribute to the magnetization M (T) only in the low-temperature limit of T < 10–20 K, and MnSb nanoprecipitates responsible for the ferromagnetic (FM) properties of In1−xMnxSb, a superparamagnetic (SP) contribution of atomic-size magnetic Mn complexes (presumably dimers) has been established. The fraction of the MnSb phase, η ∼ 1–4%, as well as the concentration, nsp ∼ (0.8–3.2) × 1019 cm−3, and the magnetic moment of the Mn dimers, μ ∼ 8–9 μB, are determined. The solubility limit of Mn in the InSb matrix, NSL ∼ 1020 cm−3, is estimated. Hysteresis in low (H < 500 Oe) magnetic fields and saturation of the magnetization in high (H > 20 kOe) magnetic fields are observed, indicating a presence of the SP and FM contributions to the dependence of M (H) up to T ∼ 500 K. The hysteresis is characterized by the coercivity field, Hc, decreasing between ∼100 and 75 Oe when T is increased from 5 to 510 K. The values of Hc are in reasonable agreement with the effect of the largest MnSb inclusions. The maximum of M (T), measured in the zero-field-cooled and the field-cooled conditions in a weak field of 500 Oe, is observed at T ∼ 510 K and is attributable to the Hopkinson effect.
Structural and magnetic properties of In1-xMnxSb: Effect of Mn complexes and MnSb nanoprecipitates / A. V., Kochura; B. A., Aronzon; K. G., Lisunov; A. V., Lashkul; A. A., Sidorenko; DE RENZI, Roberto; S. F., Marenkin; M., Alam; A. P., Kuzmenko; E., Lähderanta. - In: JOURNAL OF APPLIED PHYSICS. - ISSN 0021-8979. - 113:(2013), p. 083905. [10.1063/1.4792652]
Structural and magnetic properties of In1-xMnxSb: Effect of Mn complexes and MnSb nanoprecipitates
DE RENZI, Roberto;
2013-01-01
Abstract
Structural and magnetic properties of the group III-V diluted magnetic semiconductor In1−xMnxSb with x = 0.005–0.06, including the nuclear magnetic resonance (NMR) investigations, are reported. Polycrystalline In1−xMnxSb samples were prepared by direct alloying of indium antimonide, manganese and antimony, followed by a fast cooling of the melt with a rate of 10–12 K/s. According to the X-ray diffraction data, part of Mn is substituted for In, forming the In1−xMnxSb matrix. Atomic force microscopy and scanning tunneling microscopy investigations provide evidence for the presence of microcrystalline MnSb inclusions (precipitates), having a size of ∼100–600 nm, and the fine structure of nanosize grains with a Gaussian distribution around the diameter of ∼24 nm. According to the NMR spectra, the majority of Mn enters the MnSb inclusions. In addition to the single Mn ions, which contribute to the magnetization M (T) only in the low-temperature limit of T < 10–20 K, and MnSb nanoprecipitates responsible for the ferromagnetic (FM) properties of In1−xMnxSb, a superparamagnetic (SP) contribution of atomic-size magnetic Mn complexes (presumably dimers) has been established. The fraction of the MnSb phase, η ∼ 1–4%, as well as the concentration, nsp ∼ (0.8–3.2) × 1019 cm−3, and the magnetic moment of the Mn dimers, μ ∼ 8–9 μB, are determined. The solubility limit of Mn in the InSb matrix, NSL ∼ 1020 cm−3, is estimated. Hysteresis in low (H < 500 Oe) magnetic fields and saturation of the magnetization in high (H > 20 kOe) magnetic fields are observed, indicating a presence of the SP and FM contributions to the dependence of M (H) up to T ∼ 500 K. The hysteresis is characterized by the coercivity field, Hc, decreasing between ∼100 and 75 Oe when T is increased from 5 to 510 K. The values of Hc are in reasonable agreement with the effect of the largest MnSb inclusions. The maximum of M (T), measured in the zero-field-cooled and the field-cooled conditions in a weak field of 500 Oe, is observed at T ∼ 510 K and is attributable to the Hopkinson effect.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
