Transport properties of high-performance all-Heusler Co2CrSi/Cu2CrAl/Co2CrSi giant magnetoresistance device

Abstract

Transport properties of giant magnetoresistance (MR) junction consisting of trilayer Co2CrSi/Cu2CrAl/Co2CrSi Heusler alloys (L21) are studied using first-principles approach based on density functional theory and the non-equilibrium Green's function method. Highly conductive channels are found in almost the entire k-plane when the magnetizations of the electrodes are parallel, while they are completely blocked in the antiparallel configuration, which leads to a high magnetoresistance ratio (the pessimistic MR ratio is nearly 100%). Furthermore, the calculated I-V curve shows that the device behaves as a good spin valve with a considerable disparity in currents under the parallel and antiparallel magnetic configurations of the electrodes. The Co2CrSi/Cu2CrAl/Co2CrSi junction could be useful for high-performance all-metallic current-perpendicular-to-plane giant magnetoresistance reading head for the next generation high density magnetic storage.

Structure, Magnetism, and Electronic Properties of Inverse Heusler Alloy Ti2CoAl/MgO(100) Herterojuction: The Role of Interfaces

“…The current record for the highest Heusler TMR observed experimentally is held by Co 2 MnSi/MgO/Co 2 MnSi, which produced a TMR ratio of 1995% at 4 K [21]. From the ab initio calculation, a theoretical TMR value of about 10 6 was detected in Co 2 CrSi/Cu 2 CrAl/Co 2 CrSi [22]. Recently, an extremely high TMR value exceeding 25,000% was detected in a binary all-Heusler stack Fe 3 Al/BiF 3 /Fe 3 Al at low bias [23].…”

“…Many Cu 2 MnAl-type Heusler alloys, such as Co 2 MnX (X = Si, Ge, Sn) [25], Mn 2 CoZ (Z = Al, Ga, In, Si, Ge, Sn, Sb), [26] and Cr 2 MnZ (Z = P, As, Sb, and Bi) [27], have been predicted with half-metallicity from theoretical ab initio calculations and experimental investigations. TMR experiments of the classic Heusler compound MTJs highlighted significant magnetoresistive effects of these junctions and their potential applications [21,22,28]. However, inverse Ti-based Heusler alloys, such as Ti 2 VAl [29], Ti 2 FeIn [30], and Ti 2 MnGa [31], have been previously predicted with "ideal" half-metallicity in the bulk phase from first-principle calculations.…”

Electronic structure and magnetic properties of quaternary Heusler alloy Co2CrGa1−Ge (x=0−1)

“…The potentially high spin polarization of Co-based full-Heusler alloys is very advantageous for obtaining high tunnel magnetoresistance (TMR) ratios in magnetic tunnel junctions (MTJs) according to Julliere's model [12]. There have been many reports in literature predicting the possibility of realizing half metallic characteristics in many new materials through ab-initio calculations [4,11,[13][14][15][16][17]. Galanakis et al calculated the electronic structure of Co 2 MnZ (Z ¼Al, Si, Ge and Sn) and discussed the origin of the band gap [1].…”

“…Co 2 CrZ compounds have recently attracted much theoretical and experimental attention [14][15][16][17] for magneto-resistive device applications. The first significant magneto-resistive effect has been observed by Block et al in Co 2 Cr 0.6 Fe 0.4 Al powder compacts [14].…”

Finely Controlled Approaches to Formation of Heusler-Alloy/Semiconductor Heterostructures for Spintronics

“…[1][2][3][4]21,22) In general, the high-temperature annealing was conducted for obtaining B2 or L2 1 ordered full-Heusler alloys, [1][2][3][4] and the high tunneling magnetoresistance and CPP-GMR effects were observed for the devices formed above 400 C. [6][7][8][9][10][11] Unfortunately, since the high-temperature annealing is not compatible with the formation of heterostructures consisting of the full-Heusler alloys and semiconductors, the low-temperature formation techniques are required. Although recent theoretical studies suggested that very large CPP-GMR effects can be seen in all-Heusler stacking structures with the electronic band matching, [23][24][25][26] the in uence of some magnetic dead layers and the atomic interdiffusion between Heusler alloys was found in actual Heusler bilayers formed by the sputtering method and the post-growth annealing even at 200 C. 27) Here we introduce our recent progress of the developments for the ne control of the formation of heterostructures consisting of B2 or L2 1 ordered Heusler-alloys and Si or Ge. First, a concept of the realization of the low-temperature heteroepitaxy for Heusler alloy/Si or Heusler alloy/Ge heterostructures is shown.…”