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Topological insulators (TIs) a new quantum state of matter predicted to have an interesting surface properties. In this report, we study the surface properties of Bi 2 Te 2 Se (BTS) topological insulators thin films. Raman measurements on BTS thin film show a strong intensity of A 1 1 g ( ∼ 62 cm - 1 ), E 2 g ( ∼ 123 cm - 1 ) and A 2 1 g ( ∼ 170 cm - 1 ) modes in addition to A 2 1 u ( ∼ 140 cm - 1 ) modes. Elemental analyses were done using X-ray photoelectron spectroscopy (XPS). Resistance versus temperature measurement reveal a magnetic field-driven metallic behavior at high temperatures and further analysis on magnetic measurement shows a diamagnetic nature of BTS film. The magneto-resistance measurements on these films exhibit a weak antilocalization effect that arises due to quantum interfering nature of topological insulators and the measured weak anti-localization effect is fitted using Hikami–Larkin–Nagaoka (HLN) model. [ABSTRACT FROM AUTHOR]

• Ion beam modification has been studied for CoFe/n-Si interfaces. • Ordered array of grains has been observed which is due to recrystallization phenomenon. • Drastic change in M-H loops from antiferromagnetic coupled phase to ferromagnetic phase has been observed. • A significant electronic transport has been observed with and without magnetic field. • Magneto-resistance of ∼7% has been estimated for the structure. Interfacial structures of ferromagnetic (FM) metal combined with semiconductor (SC) are key step for realizing spintronic devices where spin degree of freedom can also be utilized in addition to the charge of electron. Tailoring of such interfaces (of FM/SC) is known to tune the magnetic, optical, structural and transport properties. Swift heavy ion irradiation (SHI) can be used as a potential tool to tailor the interfaces. In our present work, effect of ion beam irradiation (100 meV Ni+7 ions) on the CoFe/n-Si interfacial structures had been studied. Thin films of CoFe was deposited by electron beam evaporation technique using CoFe metallic alloy on Si substrate. The realized interfacial structure was characterized from structural, morphological and magnetic point of view. The surface exhibits grainy structure with very fine domain (∼50 nm) on the irradiation. Electronic transport study across the interface shows an increase in current on irradiation with significant magnetic field sensitivity and a magnetoresistance of ∼7% has been observed. The observed results of increased magnetization and enhanced magnetic field sensitivity has been understood in the realm of irradiation induced interfacial intermixing across the interfaces. The chemical phases formed and nature of the interface as a result of irradiation was probed by X-ray photoelectron spectroscopy (XPS) study which confirms the formation of various silicide phases along with the metallic phase. The results were also compared with our earlier studies [15–16] on CoFe/n-Si system and found that fluence of 1 × 1011 ions/cm2 seems significant to result in interesting magnetic and transport properties without much damage to interface. [ABSTRACT FROM AUTHOR]

Magnetic and magneto-transport properties of thin layers of the (Ga,Mn)(Bi,As) quaternary dilute magnetic semiconductor grown by the low-temperature molecular-beam epitaxy technique on GaAs substrates have been investigated. Ferromagnetic Curie temperature and magneto-crystalline anisotropy of the layers have been examined by using magneto-optical Kerr effect magnetometry and low-temperature magneto-transport measurements. Post-growth annealing treatment of the layers has been shown to enhance the hole concentration and Curie temperature in the layers. A significant increase in the magnitude of magneto-transport effects caused by incorporation of a small amount of Bi into the (Ga,Mn)As layers, revealed in the planar Hall effect (PHE) measurements, is interpreted as a result of enhanced spin-orbit coupling in the (Ga,Mn)(Bi,As) layers. A two-state behaviour of the planar Hall resistance at zero magnetic field provides its usefulness for applications in non-volatile memory devices. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties of thin films of the (Ga,Mn)(Bi,As) quaternary diluted magnetic semiconductor grown by the low-temperature molecular-beam epitaxy technique on GaAs substrates have been investigated. High-resolution X-ray diffraction has been applied to characterize the structural quality and misfit strain in the films. Ferromagnetic Curie temperature and magneto-crystalline anisotropy of the films have been examined by using SQUID magnetometry and low-temperature magneto-transport measurements. Post-growth annealing treatment of the films has been shown to reduce the strain in the films and to enhance their Curie temperature. Significant increase in the magnitude of magneto-transport effects caused by incorporation of a small amount of Bi into the films is interpreted as a result of enhanced spin-orbit coupling in the (Ga,Mn)(Bi,As) films. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: Pulsed laser deposited thin films of electron doped La0.7Ce0.3MnO3 have been irradiated with 200MeV Ag ions at different fluence values. The irradiation driven alteration on the pink noise (1/f noise), electrical and magneto-transport properties have been investigated. It is observed that the irradiation fluence adjusts the metal–insulator transition temperature, the magnetic field response to the resistance and the noise values. These parameters may assist in tuning these materials for applications. The film irradiated with the lower fluence value of 5×1010 ions/cm2 enhances the performance at room temperature. However, the film irradiated at higher fluence values manipulates these functionalities at lower temperature regime. The normalized noise values in the irradiated films are higher in ferromagnetic regime than in the paramagnetic regime. The observations have been explained on the basis of effects of the presence of swift heavy ion irradiation induced strain and defects. [Copyright &y& Elsevier]

Abstract: The influence of swift heavy ion (SHI) irradiation on electronic transport properties of epitaxial thin films of La0.75Ca0.25MnO3 is studied. The films were irradiated with 250MeV Ag17+ beam at fluence range 1010–1012 ions/cm2. A systematic variation in metal–insulator transition temperature (T p) and peak resistivity have been observed. At low fluence value (3×1010 ions/cm2) the T p is increased by 34K. With the increase in fluence it decreases but remain at upper side up to the fluence value of 3×1011 ions/cm2 as compared to the unirradiated film. The peak resistivity is also decreasing with the increase in fluence up to 3×1011 ions/cm2 and then increases with further increase of fluence. The temperature coefficient resistivity (TCR) is also increased with the fluence. The observed effects are correlated with the effects produced by the applications of hydrostatic pressure. The results are discussed in terms of SHI irradiation induced structural strains in the films. [Copyright &y& Elsevier]

• Large grain Ge rich polycrystalline SiGe thin film on glass at 350 °C using Al-induced layer exchange crystallization. • Degenerate p -type doping from residual Al atoms. • Weak anti-localization effect below 10 K in magnetoresistance. We report the low-temperature magneto-transport properties of a polycrystalline-SiGe thin film realized on glass at 350 ℃ via Al-induced layer exchange crystallization. The film exhibits a degenerate p -type behavior, and we observed evidence of weak-antilocalization (WAL) effect that manifests as an anomalous positive magnetoresistance (MR) below 10 K and weak magnetic fields (B) between ± 1 Tesla. While the spin–orbit coupling length is nearly constant at ~ 40 nm, the temperature dependence of phase-coherence length, which has a maximum value at 4 K (~131 nm), indicates hole-hole scattering as the predominant de-phasing mechanism. This result shows the degenerate Al doping causes the WAL effect in the present system. [ABSTRACT FROM AUTHOR]

In this work, we developed and fabricated a paper-based anisotropic magneto-resistive sensor using a sputtered permalloy (Ni 81 Fe 19 ) thin film. To interpret the characteristics of the sensor, we proposed a computational model to capture the influence of the stochastic fiber network of the paper surface and to explain the physics behind the empirically observed difference in paper-based anisotropic magneto-resistance (AMR). Using the model, we verified two main empirical observations: (1) The stochastic fiber network of the paper substrate induces a shift of 45 ∘ in the AMR response of the paper-based Ni 81 Fe 19 thin film compared to a Ni 81 Fe 19 film on a smooth surface as long as the fibrous topography has not become buried. (2) The ratio of magnitudes of AMR peaks at different anisotropy angles and the inverted AMR peak at the 90 ∘ -anisotropy angle are explained through the superposition of the responses of Ni 81 Fe 19 inheriting the fibrous topography and smoother Ni 81 Fe 19 on buried fibrous topographies. As for the sensitivity and reproducibility of the sensor signal, we obtained a maximum AMR peak of 0.4 % , min-max sensitivity range of [ 0.17 , 0.26 ] % , average asymmetry of peak location of 2.7 kA m within two consecutive magnetic loading cycles, and a deviation of 250–850 A m of peak location across several anisotropy angles at a base resistance of ∼100 Ω. Last, we demonstrated the usability of the sensor in two educational application examples: a textbook clicker and interactive braille flashcards. [ABSTRACT FROM AUTHOR]