Giant tunnel magnetoresistance in magnetic tunnel junctions with a crystalline MgO(0 0 1) barrier

Yuasa, Shinji; Djayaprawira, D.D.

doi:10.1088/0022-3727/40/21/r01

Cited by 571 publications

(414 citation statements)

References 57 publications

Supporting

Mentioning

393

Contrasting

Unclassified

Order By: Relevance

“…1 Currently, a room-temperature TMR ratio as high as 500% can be reached in junctions made of polycrystalline Fe (more precisely, CoFeB) sandwiching a thin MgO insulating layer. 2 Despite such huge TMR ratios, the Fe/MgO system presents two limiting aspects for future applications.…”

Section: Introductionmentioning

confidence: 99%

Electronic transport through EuO spin-filter tunnel junctions

et al. 2012

View full text Add to dashboard Cite

Epitaxial spin-filter tunnel junctions based on the ferromagnetic semiconductor europium monoxide (EuO) are investigated by means of density functional theory. In particular, we focus on the spin transport properties of Cu(100)/EuO(100)/Cu(100) junctions. The dependence of the transmission coefficient and the current-voltage curves on the interface spacing and EuO thickness is explained in terms of the EuO density of states and the complex band structure. Furthermore, we also discuss the relation between the spin transport properties and the Cu-EuO interface geometry. The level alignment of the junction is sensitively affected by the interface spacing, since this determines the charge transfer between EuO and the Cu electrodes. Our calculations indicate that EuO epitaxially grown on Cu can act as a perfect spin filter, with a spin polarization of the current close to 100%, and with both the Eu-5d conduction-band and the Eu-4f valence-band states contributing to the coherent transport. For epitaxial EuO on Cu, a symmetry filtering is observed, with the 1 states dominating the transmission. This leads to a transport gap larger than the fundamental EuO band gap. Importantly, the high spin polarization of the current is preserved up to large bias voltages.

show abstract

Section: Introductionmentioning

confidence: 99%

Electronic transport through EuO spin-filter tunnel junctions

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Note the great interest of thin silicide properties as Mg 2 Si for thermoelectric applications 19 or MgB 2 superconducting thin films on Si(100). 20 Here, the choice of Mg is motivated by the high potentiality of its oxide as an insulating barrier for magnetic tunnel junctions 21,22 and siliconbased spintronics. 2 All experiments were performed in an ultra-high vacuum (UHV) chamber equipped with a commercial Omicron variable temperature-scanning tunneling microscopy, an Omicron Spectra-low energy electron diffraction (LEED), and a Riber CMA Auger spectrometer.…”

mentioning

confidence: 99%

Surface-interface exploration of Mg deposited on Si(100) and oxidation effect on interfacial layer

Sarpi

Daineche

Girardeaux

et al. 2015

Applied Physics Letters

View full text Add to dashboard Cite

International audienceUsing scanning tunneling microscopy and spectroscopy, Auger electron spectroscopy, and low energy electron diffraction, we have studied the growth of Mg deposited on Si(100)-(2 x 1). Coverage from 0.05 monolayer (ML) to 3 ML was investigated at room temperature. The growth mode of the magnesium is a two steps process. At very low coverage, there is formation of an amorphous ultrathin silicide layer with a band gap of 0.74 eV, followed by a layer-by-layer growth of Mg on top of this silicide layer. Topographic images reveal that each metallic Mg layer is formed by 2D islands coalescence process on top of the silicide interfacial layer. During oxidation of the Mg monolayer, the interfacial silicide layer acts as diffusion barrier for the oxygen atoms with a decomposition of the silicide film to a magnesium oxide as function of O2 exposure

show abstract

“…Experimentally for Fe/MgO/Fe epitaxial MTJs, a peak in the tunnel spectra (d 2 V /dI 2 vs V ) for the AP state slightly above 1000 mV has indeed been observed by Ando et al [27] and related to the 1↓ band conductance anomaly just described. In a discussion of this anomaly by Yuasa and Djayaprawira [1], a steplike increase of the tunnel conductance was schematically assumed as soon as the 1↓ band starts to conduct. The tunnel spectrum, however, shows a broad peak instead of a δ-function [27].…”

Section: Resultsmentioning

confidence: 99%

“…In the AP state of a bcc-Co/MgO/bcc-Co MTJ, the 1 band of bcc-Co will not conduct for low bias, and the 2 , 5 , and 2 bands will not contribute to conduction because the respective majority spin bands are well below the Fermi level; therefore, coherent tunneling is totally suppressed and a markedly higher TMR ratio is expected compared to a MTJ with Fe electrodes [1,8]. The TMR ratio will not approach infinity because an incoherent background conductance will be present in a real junction.…”

Section: Resultsmentioning

confidence: 99%

“…The TMR ratio is defined as TMR = (R AP − R P )/R p , where R P (R AP ) are the resistance values for the parallel [P](antiparallel [AP]) magnetization state of the two ferromagnetic layers. The origin of the difference in resistance between the P and AP state is the spin dependence of the tunneling probability of electrons and, hence, the spin polarization of the tunneling current through the barrier [1].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Conductance anomalies of CoFeB/MgO/CoFeB magnetic tunnel junctions

et al. 2014

View full text Add to dashboard Cite

The I -V characteristics of CoFeB/MgO/CoFeB magnetic tunnel junctions show pronounced nonlinearities which are relevant both for sensor applications and for the basic understanding of spin-dependent tunneling. To study the relation between the tunnel characteristics and the tunnel magnetoresistance (TMR) ratio, a series of CoFeB/MgO/CoFeB junctions was annealed with stepwise increasing annealing time at different temperatures. The related TMR ratio and the I -V characteristics were measured in the temperature range between 15 K and 300 K. This allowed the comparison of I -V characteristics of the same junction for TMR ratios between 25% and 150% at 300 K thus eliminating the influence of variations in the preparation process of separate individual samples. In addition to a zero bias anomaly observed in particular at low temperatures and for large TMR ratios, a conductance anomaly in the I -V curves was observed around a bias voltage of 350 mV. A general correlation between the deviation from Ohmic I -V characteristics and the TMR ratio was found both for parallel and antiparallel magnetizations of both ferromagnetic layers. This means that the shape of the I -V curves directly scales with the spin polarization of the tunneling current and the proportion of coherent electron tunneling. Both the 350 mV conductance anomaly and the correlation between non-Ohmic characteristics and the TMR ratio can be explained by considering the contributions of the relevant majority and minority spin bands of the ferromagnetic contacts.

show abstract

Giant tunnel magnetoresistance in magnetic tunnel junctions with a crystalline MgO(0 0 1) barrier

Cited by 571 publications

References 57 publications

Electronic transport through EuO spin-filter tunnel junctions

Electronic transport through EuO spin-filter tunnel junctions

Surface-interface exploration of Mg deposited on Si(100) and oxidation effect on interfacial layer

Conductance anomalies of CoFeB/MgO/CoFeB magnetic tunnel junctions

Contact Info

Product

Resources

About