Current-perpendicular-to-plane magnetoresistance in epitaxial Co2MnSi∕Cr∕Co2MnSi trilayers

Yakushiji, Kay; Saito, K.; Mitani, Seiji; Takanashi, Kōki; Takahashi, Y. K.; Hono, K.

doi:10.1063/1.2207987

Cited by 134 publications

(68 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4 In these materials the majority spin states have a metallic character with a nonzero density of states (DOS) at the Fermi level, while the minority spin states have a band gap at the Fermi level, resulting in 100% spin polarization at the Fermi level (E F ). To date there are many materials predicted to be half-metals at room temperature, and among them, the L2 1 ordered full Heusler alloys Co 2 MnSi and Co 2 MnGe are promising candidate for spintronics applications due to their high Curie temperatures, 985 K for Co 2 MnSi and 905 K for Co 2 MnGe.…”

Section: Introductionmentioning

confidence: 99%

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

View full text Add to dashboard Cite

We have studied the electronic and magnetic states of Mn and Co atoms at the Co 2 Mn β Ge 0.38 (CMG)/MgO (β = 0.67-1.8) interfaces, which constitute CMG/MgO/CMG magnetic tunnel junctions, by means of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroisms (XMCDs) at the Mn and Co L 2,3 edges and compared the deduced Co and Mn magnetic moments by the density-functional calculations with the coherent potential approximation (CPA). As the Mn content β increased, the intensity of Mn L 2,3 XMCD decreased, in agreement with the result of the CPA calculation, which showed the resultant reduction of charges and spin moment on Mn atoms because of the delocalization of Mn 3d electrons with increasing β. The Co spin magnetic moment for all the samples increased with decreasing β, again consistent with the present calculation and the previous density-functional calculation by Picozzi et al. that the Co Mn antisite has a larger magnetic moment than that of Co atoms at the regular sites and reduces the spin polarization at the Fermi level and hence the tunnel magnetoresistance ratio.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

View full text Add to dashboard Cite

show abstract

“…3 Thus, the implementation of Heusler compounds in CPP-GMR spinvalves seems desirable. [4][5][6] However, annealing temperatures higher than 300°C which are usually necessary to obtain the highly ordered L2 1 phase are incompatible with reliable device fabrication. An enhancement of the CPP-GMR was also observed by addition of Al to a CoFe alloy, even with a low annealing temperature T ϳ 250°C.…”

mentioning

confidence: 99%

Local formation of a Heusler structure in CoFe–Al alloys

Wurmehl

Jacobs

Swagten

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

“…Recently, extensive studies have been conducted to apply these Co-based Heusler alloy thin films to spintronic devices. [1][2][3][4][5][6][7][8] One Co-based Heusler alloy in particular, Co 2 MnSi ͑CMS͒, has attracted interest 2,4,5,7 because of its theoretically predicted half-metallic nature with a relatively large energy gap of 0.4-0.8 eV for its minority-spin direction. 9,10 We recently developed fully epitaxial magnetic tunnel junctions ͑MTJs͒ with CMS thin films as both lower and upper electrodes and with a MgO tunnel barrier ͑CMS/MgO/CMS MTJs, hereafter CMS-MTJs͒.…”

mentioning

confidence: 99%

Influence of film composition in Co2MnSi electrodes on tunnel magnetoresistance characteristics of Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions

Ishikawa

Liu

Taira

et al. 2009

Applied Physics Letters

View full text Add to dashboard Cite

Fully epitaxial Co 2 MnSi ͑CMS͒/MgO/CMS magnetic tunnel junctions ͑MTJs͒ with various values of Mn composition ␣ in Co 2 Mn ␣ Si electrodes were fabricated and the influence of ␣ on the tunnel magnetoresistance ͑TMR͒ characteristics of these MTJs was investigated. MTJs with Mn-rich CMS electrodes showed TMR ratios, up to 1135% at 4.2 K and 236% at room temperature for ␣ = 1.29, exceeding those of MTJs with CMS electrodes having an almost stoichiometric composition. A possible origin of the higher TMR ratios for ␣ beyond 1.0 is a decreased density of gap states existing around the Fermi level in the half-metal gap caused by the suppression of Co Mn antisites, where a Mn site is replaced by a Co atom, for Mn-rich CMS electrodes. © 2009 American Institute of Physics. ͓doi:10.1063/1.3272926͔A highly efficient spin-polarized electron source is a key element for spintronic devices. Half-metallic ferromagnets ͑HMFs͒ are the most suitable materials for spin-polarized electron sources because they provide complete spin polarization at the Fermi level ͑E F ͒. Among HMFs, Co-based Heusler alloys are especially promising due to their high Curie temperatures, which are well above room temperature ͑RT͒. Recently, extensive studies have been conducted to apply these Co-based Heusler alloy thin films to spintronic devices. [1][2][3][4][5][6][7][8] One Co-based Heusler alloy in particular, Co 2 MnSi ͑CMS͒, has attracted interest 2,4,5,7 because of its theoretically predicted half-metallic nature with a relatively large energy gap of 0.4-0.8 eV for its minority-spin direction. 9,10 We recently developed fully epitaxial magnetic tunnel junctions ͑MTJs͒ with CMS thin films as both lower and upper electrodes and with a MgO tunnel barrier ͑CMS/MgO/CMS MTJs, hereafter CMS-MTJs͒. [11][12][13] Epitaxial layer structures with a CMS electrode and a MgO barrier are beneficial for creating highly spin-polarized current due to the potentially half-metallic nature of CMS electrodes and the coherent tunneling through the single-crystalline MgO barrier. [14][15][16] We have demonstrated relatively high tunnel magnetoresistance ͑TMR͒ ratios around 180% at RT and 700% at 4.2 K for CMS-MTJs. 11,13 Furthermore, we found strong evidence for the existence of interface states in the interfacial region of CMS electrodes facing a MgO tunnel barrier, as well as evidence of residual states in the bulk region of upper CMS electrodes, in both cases in the half-metal gap for minority spins around E F from analysis of the dI / dV and d 2 I / dV 2 characteristics of CMS-MTJs. 12,13 The film composition of CMS electrodes used in our previous study [11][12][13] was Co 2 Mn 0.91 Si 0.93 , a slightly Co-rich composition with respect to the stoichiometry ͑or a slightly Mn-and Si-deficient composition͒. Film composition deviation from the stoichiometry inevitably induces some kinds of structural defect. The influence of defects in CMS on the half-metallic electronic structure has been investigated theoretically. [17][18][19][20] It has been pointed out that the half...

show abstract

Current-perpendicular-to-plane magnetoresistance in epitaxial Co2MnSi∕Cr∕Co2MnSi trilayers

Cited by 134 publications

References 18 publications

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Local formation of a Heusler structure in CoFe–Al alloys

Influence of film composition in Co2MnSi electrodes on tunnel magnetoresistance characteristics of Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions

Contact Info

Product

Resources

About