Highly ordered Co2FeSi Heusler alloys grown on Ge(111) by low-temperature molecular beam epitaxy

Kasahara, Kenji; Yamamoto, Keisuke; Yamada, Shinya; Murakami, T.; Hamaya, Kohei; Mibu, Ko; Miyao, Masanobu

doi:10.1063/1.3350915

Cited by 53 publications

(55 citation statements)

References 23 publications

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“…Even though Co 2 FeSi alloy appears to be half-metallic only theoretically and only under stringent conditions on U ef f , it has been extensively referenced in the literature as such. [17][18][19][20][21][22] This prediction, however, is at odds with several experimental measurements based on Point Contact Andreev Reflection (PCAR) spectroscopy 17,22,23 , which yield values of P ∼50%, far lower than 100%. The goal of this Rapid Communication is to reconcile the results of computational predictions with experimental measurements for Co 2 FeSi.…”

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confidence: 39%

On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy

et al. 2013

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confidence: 39%

On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy

et al. 2013

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“…Figures 4(b) and 4(c) show the carrier concentration (n) and Hall mobility (μ H ) of CFS/STO films, respectively. With decreasing thickness, a monotonic increase in n is observed with a highest value of 3.3×10 21 cm −3 at 2 K for 12 nm film, which can be qualitatively explained by considering the parallel resistor model, where…”

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confidence: 86%

“…[21][22][23][24][25] The substrates used in present study were (001) LAO, MgO, NdGaO 3 (NGO), and STO, whose face diagonal matches quite well with the lattice parameter (≈0.565 nm) of CM(F)S. We have deposited a large number (over 70) of highly ordered single phase thin films of CM(F)S under various growth environments using a pulsed laser ablation technique. 26 The growth rate of a 0.0065 nm per laser pulse allows the synthesis of smooth and uniform epitaxial films.…”

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confidence: 99%

Two-dimensional electron-gas-like charge transport at the interface between a magnetic Heusler alloy and SrTiO3

et al. 2014

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We report remarkably low residual resistivity, giant residual resistivity ratio, free-electron-like Hall resistivity, and high mobility (≈10 4 cm 2 V −1 s −1 ) charge transport in epitaxial films of Co 2 MnSi and Co 2 FeSi grown on (001) SrTiO 3 . This unusual behavior is not observed in films deposited on other cubic oxide substrates of comparable lattice parameters. The scaling of the resistivity with thickness of the films allows the extraction of interface conductance, which can be attributed to a layer of oxygen vacancies confined within 1.9 nm of the interface as revealed by atomically resolved electron microscopy and spectroscopy. The high mobility transport observed here at the interface of a fully spin polarized metal is potentially important for spintronics applications. The seemingly extraordinary electronic transport observed in epitaxial films of LaAlO 3 (LAO), LaTiO 3 (LTO), and related perovskites grown on TiO 2 terminated (001) SrTiO 3 (STO) has taken central stage in condensed matter physics research in recent years.1-4 The origin of two-dimensional electron gas (2DEG), whose mobility and carrier density depend strongly on growth temperature and oxygen partial pressure, 1-3 and which can be modified further by ultraviolet light 2 and electric field, 5 has been attributed to interfacial factors such as atomic relaxation, electronic reconstruction, cation intermixing, and/or creation of oxygen vacancies. 6 The electronic properties of such interfaces have been studied extensively owing to unusual charge transport, 1,7 magnetism, [8][9][10] two-dimensional superconductivity, 11-13 and quantum oscillation in the conductivity.14,15 While several types of oxide overlayers show unusually large interfacial conductivity, 16,17 the common denominator in all these cases is STO, which even without any overlayer, but subjected to subtle surface treatments, can show fascinating 2D electronic behavior. 18,19 Departing from the commonly used approach of growing oxide overlayers, here we show a similar electronic transport realized at the interface of a half-metallic Heusler alloy and STO. The Heusler compounds have generated considerable interest in recent years due to a myriad of properties encompassing half-metallicity, shape memory effect, thermoelectricity, superconductivity, and topologically inhibited conducting states. 20 While our discovery of a highly conducting interface between Heusler alloys and STO can have potential technological applications, the fundamental mechanism for the origin of such a state brings into question the several interpretations given for 2DEG previously.The thin films of Co-based full-Heusler alloys such as Co 2 FeSi (CFS) and Co 2 MnSi (CMS) have been grown on a variety of semiconductors and oxide dielectrics. [21][22][23][24][25] The substrates used in present study were (001) LAO, MgO, NdGaO 3 (NGO), and STO, whose face diagonal matches quite well with the lattice parameter (≈0.565 nm) of CM(F)S. We have deposited a large number (over 70) of highly ordered single phase thin ...

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“…However, FeMn 2 Ge (T C = 233 K) and Fe 2 MnGe (T C = 433 K) both form in the Heusler structure type and are ferromagnetic as are Co 2 MnGe (T C = 905 K) and Rh 2 MnGe (T C = 450 K) [83]. There are several investigations of these types of materials grown on silicon and germanium substrates to assess their compatibility with silicon technology [87][88][89][90][91]. A few of these materials, Co 2 MnSi, Co 2 FeSi [92], and Co 2 MnGe, are predicted to be half metallic with high Curie Temperatures and are well lattice matched to GaAs [93,94].…”

Section: Silicides and Germanidesmentioning

confidence: 99%

Si-Based Magnetic Semiconductors

DiTusa

2015

Handbook of Spintronics

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The efforts over the past decade to identify and characterize magnetic semiconducting systems that would be compatible with present-day silicon technologies are reviewed. Investigations that have explored transition metal doping of the group IV semiconductors silicon and germanium are discussed along with intermetallic compounds such as silicides and germanides that may play the role of a magnetic semiconducting source of polarized electrons. Thin films and nanostructures of these materials have been grown by a number of synthesis techniques, and the resulting structural properties, including the important issue of homogeneity of dopants, are critically surveyed. The resulting magnetic and carrier transport properties are also reviewed. List of Abbreviations

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Highly ordered Co2FeSi Heusler alloys grown on Ge(111) by low-temperature molecular beam epitaxy

Cited by 53 publications

References 23 publications

On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy

On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy

Two-dimensional electron-gas-like charge transport at the interface between a magnetic Heusler alloy and SrTiO3

Si-Based Magnetic Semiconductors

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