Is<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>CrO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>Fully Spin Polarized? Analysis of Andreev Spectra and Excess Current

Löfwander, Tomas; Grein, Roland; Eschrig, Matthias

doi:10.1103/physrevlett.105.207001

Cited by 40 publications

(95 citation statements)

References 25 publications

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“…7 Electronic and magnetic properties of bulk 8 and epitaxial 9 CrO 2 have also been investigated theoretically. 10 Single-layer CoO 2 has played an important role in understanding the superconducting properties of nickel and cobalt oxide based compounds. In these structures, single layers of CoO 2 are separated generally by thick insulating layers of Na + ions and H 2 O molecules.…”

Section: ■ Introductionmentioning

confidence: 99%

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

2012

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Recent studies have revealed that single-layer transition-metal oxides and dichalcogenides (MX 2 ) might offer properties superior to those of graphene. So far, only very few MX 2 compounds have been synthesized as suspended single layers, and some of them have been exfoliated as thin sheets. Using first-principles structure optimization and phonon calculations based on density functional theory, we predict that, out of 88 different combinations of MX 2 compounds, several of them can be stable in free-standing, single-layer honeycomb-like structures. These materials have two-dimensional hexagonal lattices and have top-view appearances as if they consisted of either honeycombs or centered honeycombs. However, their bonding is different from that of graphene; they can be viewed as a positively charged plane of transition-metal atoms sandwiched between two planes of negatively charged oxygen or chalcogen atoms. Electron correlation in transition-metal oxides was treated by including Coulomb repulsion through LDA + U calculations. Our analysis of stability was extended to include in-plane stiffness, as well as ab initio, finite-temperature molecular dynamics calculations. Some of these single-layer structures are direct-or indirect-band-gap semiconductors, only one compound is half-metal, and the rest are either ferromagnetic or nonmagnetic metals. Because of their surface polarity, band gap, high in-plane stiffness, and suitability for functionalization by adatoms or vacancies, these single-layer structures can be utilized in a wide range of technological applications, especially as nanoscale coatings for surfaces contributing crucial functionalities. In particular, the manifold WX 2 heralds exceptional properties promising future nanoscale applications.

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Section: ■ Introductionmentioning

confidence: 99%

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

2012

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“…The SMM model has been proposed to account for these differences. In such cases, the conductance spectra observed by PCS will differ considerably from the predictions of the modified BTK model [3,19]. In ref.…”

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“…Here we examine the spectroscopic information from single S/F, Pb/CrO 2 contacts using CrO 2 thin films grown on Al 2 O 3 or TiO 2 substrates [11,12]. We do this in the context of the Mazin modified Blonder-Tinkham-Klapwijk (BTK) [13,14] and the more recent LRSTPE spin mixing model (SMM) [3,15] and find that the latter suggests that CrO 2 has strong intrinsic spin mixing properties independent of the substrate on which it is grown.…”

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confidence: 99%

“…The technique has been used extensively to investigate the transport spin polarization of candidate materials for spintronics [1,16] using the modified BTK model. In this model, the spectra can be fitted using four parameters: the superconducting gap, Δ, a measure of the interface scattering, Z (a spin-independent delta-function parameter), the spin polarisation of the transport carriers, P and either a spreading resistance, r s , that captures the series resistance of the film as is used here [3,17], or a spectral broadening parameter that incorporates thermal and non-thermal smearing, ω [16]. Within the modified BTK model, the spins are treated equally as they cross the interface and no consideration is given for effects such as spin-dependent scattering [18].…”

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confidence: 99%

“…In ref. [3], two independent measures were proposed to distinguish between the two models: Using the variation of the zero-bias conductance G 0 of a contact, and the evolution of the excess current I ex measured at large voltage (eV Δ), normalised as I ex R n /Δ, where R n is the normal state resistance, both as a function of temperature [3].…”

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Andreev spectroscopy of CrO ₂ thin films on TiO ₂ and Al ₂ O ₃

Yates¹,

Anwar²,

Aarts³

et al. 2013

EPL

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Here we analyse the spectroscopic information gathered at a number of single CrO2/Pb interfaces. We examine thin films requiring additional interfacial layers to generate long-range spin triplet proximity effect superconductivity (CrO2/TiO2) or not (CrO2/Al2O3). We analyse the data using two theoretical models and explore the use of a parameter-free method to determine the agreement between the models and experimental observations, showing the necessary temperature range that would be required to make a definitive statement. The use of the excess current as a further tool to distinguish between models is also examined. The analysis of the spectra demonstrates that the temperature dependence of the normalised zero-bias conductance is independent of the substrate onto which the films are grown. This result has important implications for the engineering of interfaces required for the long-range spin triplet proximity effect.

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Organic Spin Valves: A Review

Devkota

Geng

Subedi

et al. 2016

Adv Funct Materials

101

106

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accelerated impressively and advanced to a range of materials and a number of techniques to verify the successful injection and transport of the SP carriers. [ 1,2,10,11 ] The effect has been realized in a variety of materials combinations such as FM fi lms, FM/anti-FM coupled layers, or FM semiconductors as the injection/detection electrodes and the metals, superconductors, inorganic semiconductors, organic semiconductors, and insulators including ferroelectric and topological insulators as the spacers. [ 1,2,[12][13][14][15][16][17][18] The GMR effect was extensively studied using non-magnetic metallic interlayer and its applications such as electric switching, magnetic recording, and sensors were suggested and employed. [ 1,2,16 ] However, all-metallic spintronic devices imposed restrictions in applications as they are characterized by short spin relaxation time (≈picosecond) and are not suitable for coherent spin manipulation. [ 1,2,19 ] To overcome these limitations, the spintronics community caught its attention towards hybrid devices with semiconductors (SCs) sandwiched in between the FM layers and continued advancing to a range of semiconducting materials. [ 2,14,[20][21][22] The organic semiconductors (OSCs) are among the youngest members of the spacer materials and were fi rst tested in the spintronic devices only about a decade ago. Nevertheless, OSC devices have been of continuously advancing research topics over the past three decades for their rich physics, fl exible chemi stry, cost effi ciency, and potential applications in new generations of electronic devices including organic light emitting diodes (OLEDs), [23][24][25] organic solar cells, [ 26,27 ] and organic fi eld effect transistor. [ 28,29 ] In fact, OLEDs have already revolutionized the modern display industry and spin-dependent devices such as organic spin valves (OSVs), OLED-based magnetic sensors, and spin-OLEDs are under intensive study to achieve their new avenues. [30][31][32] This increasing interest on organic electronics is for their several distinctions over inorganic counterparts. [19][20][21]33,34 ] Electronically, the band theory explains the electric transport in inorganic SCs while charge hopping is the main transport mechanism in the OSCs with much smaller carrier mobility. This is a favorable condition for large electron-hole pair recombination without the need of using a p-n junction structure. [23][24][25] Spintronically, the inorganic SCs contain heavy atoms giving rise to a large spin-orbit coupling (SOC), which is a response of the electron spin degree of freedom to its orbital environment. The strength of the SOC in solids depends upon the nature of orbital wave functions of electrons and the materials structure. [ 35 ] In case of hydrogenic wave-function-like electrons (s-orbital electrons), it is Organic spintronics is an emerging and potential platform for future electronic devices. Signifi cant progress has been made in understanding the spin injection, manipulation, and detection in organic spin valves in the p...

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IsCrO2Fully Spin Polarized? Analysis of Andreev Spectra and Excess Current

Cited by 40 publications

References 25 publications

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Andreev spectroscopy of CrO ₂ thin films on TiO ₂ and Al ₂ O ₃

Organic Spin Valves: A Review

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IsCrO2Fully Spin Polarized? Analysis of Andreev Spectra and Excess Current

Cited by 40 publications

References 25 publications

Stable, Single-Layer MX2 Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Stable, Single-Layer MX2 Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Andreev spectroscopy of CrO 2 thin films on TiO 2 and Al 2 O 3

Organic Spin Valves: A Review

Contact Info

Product

Resources

About

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Stable, Single-Layer MX₂ Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure

Andreev spectroscopy of CrO ₂ thin films on TiO ₂ and Al ₂ O ₃