Electric field modulation of magnetic anisotropy in perpendicularly magnetized Pt/Co structure with a Pd top layer

Hibino, Yuki; Koyama, Tanetoshi; Obinata, Aya; Miwa, Kenji; Ono, Shimpei; Chiba, Daichi

doi:10.7567/apex.8.113002

Cited by 36 publications

(30 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5,6 The achievement of the VCMA effect in MgO-based MTJs 7 and the demonstration of high-speed responses, such as voltage-induced ferromagnetic resonance (FMR) excitation, 8,9 spin-wave excitation 10 and dynamic magnetization switching, [11][12][13][14] have brought great changes to research in this field. Modulations of the Curie temperature, 15 domain wall propagation, 16,17 interfacial Dzyaloshinskii-Moriya interaction 18 and proximity-induced magnetism 19 have also been demonstrated. These results indicate the feasibility of constructing voltage-driven spintronic devices, such as voltage-torque magnetoresistive random access memory devices.…”

Section: Introductionmentioning

confidence: 99%

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

et al. 2017

View full text Add to dashboard Cite

Voltage control of spin enables both a zero standby power and ultralow active power consumption in spintronic devices, such as magnetoresistive random-access memory devices. A practical approach to achieve voltage control is the electrical modulation of the spin-orbit interaction at the interface between 3d-transition-ferromagnetic-metal and dielectric layers in a magnetic tunnel junction (MTJ). However, we need to initiate a new guideline for materials design to improve both the voltage-controlled magnetic anisotropy (VCMA) and perpendicular magnetic anisotropy (PMA). Here we report that atomic-scale doping of iridium in an ultrathin Fe layer is highly effective to improving these properties in Fe/MgO-based MTJs. A large interfacial PMA energy, K i,0 , of up to 3.7 mJ m − 2 was obtained, which was 1.8 times greater than that of the pure Fe/MgO interface. Moreover, iridium doping yielded a huge VCMA coefficient (up to 320 fJ Vm − 1 ) as well as high-speed response. First-principles calculations revealed that Ir atoms dispersed within the Fe layer play a considerable role in enhancing K i,0 and the VCMA coefficient. These results demonstrate the efficacy of heavy-metal doping in ferromagnetic layers as an advanced approach to develop high-density voltage-driven spintronic devices. NPG Asia Materials (2017) 9, e451; doi:10.1038/am.2017.204; published online 5 December 2017 INTRODUCTIONSpintronic devices, such as a magnetoresistive random-access memory device using a MgO-based magnetic tunnel junction (MTJ), 1,2 are expected to reduce the standby power of future computing systems by utilizing the non-volatile feature of magnetism. However, one significant challenge emerges from reducing the energy for information writing: magnetization switching. This issue is caused by electriccurrent-based operations of spintronic devices using electric-currentinduced magnetic fields, spin-transfer torque (STT) and spin-orbit torque based on the spin Hall effect rather than the electric-field-based operations presently used for semiconductor devices. For example, recent developments of STT-magnetoresistive random access memory have achieved~100 fJ per bit writing energies, 3 which corresponds to 10 7 k B T, where k B is the Boltzmann constant and T is the temperature (assumed to be 300 K here). In contrast, the energy required for maintaining magnetic information, that is, thermal stability, is between 60 k B T and 100 k B T. This large energy gap between data writing and retention, on the order of 10 5 , mainly originates

show abstract

Section: Introductionmentioning

confidence: 99%

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

et al. 2017

View full text Add to dashboard Cite

show abstract

“…4(b), although the Pt layer thickness (1.3 nm) is less than that of the Pd layer (1.7 nm) in Pt/Co/Pd sample. The proximity induced moment decreased along the deposition direction with increasing Pt or Pd thickness and the limit of the distance at which the induced moment vanished is ∼2 nm from the surface of the Co underlayer for both Pd 13 and Pt. 19,25 Thus, larger magnetic moment is expected to be induced at the Pt surface in the present Pt/Co/Pt sample than that at the Pd surface of the Pt/Co/Pd sample.…”

Section: B Electric Field Effect Measurementmentioning

confidence: 99%

“…4,[10][11][12][13][14][15] There have been a number of reports on the electric field effect on magnetism in metallic magnetic materials using EDL capacitors, such as a large change in the Curie temperature T C for ultra-thin layers of Co, 4 magnetic signal enhancement in non-magnetic Pt, 11 modulation of the proximity-induced magnetic moment in Pd, 12 and highly efficient electric field modulation of the magnetic anisotropy in ferromagnetic Pd. 13 An identification of the difference of the mechanism (the charge accumulation effect or the redox [16][17][18] ) has also been discussed using an EDL capacitor with a Co electrode. 14 In this paper, we focus on the EDL capacitor with a Pt electrode, where a magnetic moment is induced owing to the proximity effect from an adjacent ferromagnetic Co underlayer.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dielectric and magnetic characterizations of capacitor structures with an ionic liquid/MgO barrier and a ferromagnetic Pt electrode

et al. 2016

View full text Add to dashboard Cite

The dielectric and magnetic properties of electric double layer (EDL) capacitor structures with a perpendicularly magnetized Pt/Co/Pt electrode and an insulating cap layer (MgO) are investigated. An electric field is applied through a mixed ionic liquid/MgO barrier to the surface of the top Pt layer, at which the magnetic moment is induced by the ferromagnetic proximity effect. The basic dielectric properties of the EDL capacitor are studied by varying the thickness of the MgO cap layer. The results indicate that the capacitance, i.e., the accumulated charge density at the Pt surface, is reduced with increasing the MgO thickness. From the MgO thickness dependence of the capacitance value, the effective dielectric constant of the ionic liquid is evaluated. Almost no electric field effect on the magnetic moment, the coercivity, or the Curie temperature is confirmed in the top Pt layer with the thickness of 1.3 nm, regardless of the presence or absence of the MgO cap layer, whereas the a clear change in the magnetic moment is observed when the top Pt layer is replaced by a Pd layer of 1.7 nm.

show abstract

“…R Hall n decreased with μ 0 H || , showing that the magnetization of the sample tilts from being perpendicular to the plane to the in-plane direction. Based on the R Hall n - μ 0 H || curve, the normalized magnetization along the hard axis ( M hard n ) is obtained using the following relationship: M hard n = sin[arccos( R Hall n )](refs 28, 29, 30). The results at 10 K for the three samples are shown in Fig.…”

mentioning

confidence: 99%

Co thin films deposited directly on ZnO polar surfaces

Chiba

Shibata

Tsukazaki

2016

Sci Rep

Self Cite

View full text Add to dashboard Cite

A ferromagnetic (FM)-metal/oxide stack is the key structure determining the performance of spintronic devices. However, the effect of the electronic polarity of the oxide on the magnetic properties of the adjacent FM-metal has not been investigated previously. Here, we report the magnetic and structural properties of Co ultra-thin films sputter deposited directly on the Zn- and O-polar surfaces of ZnO substrates. The magnetic anisotropy and Curie temperature exhibit dramatic polarity-dependent differences for films on these surfaces. Structural analyses reveal that the heterointerface of the Co/O-polar surface is rather diffusive, whereas that of the Co/Zn-polar surface is atomically flat. These results suggest that the surface polarity plays a key role in determining the properties of the film. This novel FM-metal/polar-oxide system is expected to add new functionality to spintronic devices and provide an ideal basis for investigating the effect of a built-in electric field on the magnetism in a metallic monolayer.

show abstract

Electric field modulation of magnetic anisotropy in perpendicularly magnetized Pt/Co structure with a Pd top layer

Cited by 36 publications

References 32 publications

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

Dielectric and magnetic characterizations of capacitor structures with an ionic liquid/MgO barrier and a ferromagnetic Pt electrode

Co thin films deposited directly on ZnO polar surfaces

Contact Info

Product

Resources

About