Absence of detectable current-induced magneto-optical Kerr effects in Pt, Ta, and W

Riego, Patricia; Vélez, Saül; Gómez‐Pérez, Juan M.; Arregi, Jon Ander; Hueso, Luis E.; Casanova, Fèlix; Berger, Andreas

doi:10.1063/1.4966276

Cited by 24 publications

(28 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The apparent sign change of the observed effect is argued to prove that the polarization rotation, amounting to 3 · 10 −4 rad for β-W, is due to the SHE. A followup study by Riego et al [20], however, does not support the above conclusions. In that work, magneto-optic ellipsometry measurements with a Kerr rotation detection limit of 10 −7 rad show that any observed currentinduced effect is related to a change of the reflectivity of the sample caused by Joule heating.…”

mentioning

confidence: 78%

“…3). In contrast, current switching by square wave modulation, as employed in previous studies [19][20][21], cannot distinguish these effects. We verified that even a slight mismatch between the amplitude of positive and negative current pulses leads to large spurious thermal signals at the fundamental modulation frequency, as discussed also in Ref.…”

Section: Adjacent Fmmentioning

confidence: 93%

“…More recently, Su et al [21] came to similar conclusions, arguing that MOKE detection would require a current density j larger than 10 8 Acm −2 . In fact, all three studies [19][20][21] used j in the order of 10 5 Acm −2 , which leads to an estimated Kerr rotation of the order of 10 −9 rad [21], five orders of magnitude smaller than the rotation reported initially [19]. Alternative optical approaches to detect the spin accumulation in NM include Brillouin light scattering [22] and second harmonic generation [23].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films

et al. 2017

View full text Add to dashboard Cite

The conversion of charge currents into spin currents in nonmagnetic conductors is a hallmark manifestation of spin-orbit coupling that has important implications for spintronic devices. Here we report the measurement of the interfacial spin accumulation induced by the spin Hall effect in Pt and W thin films using magneto-optical Kerr microscopy. We show that the Kerr rotation has opposite sign in Pt and W and scales linearly with current density. By comparing the experimental results with ab initio calculations of the spin Hall and magneto-optical Kerr effects, we quantitatively determine the current-induced spin accumulation at the Pt interface as 5×10^{-12} μ_{B} A^{-1} cm^{2} per atom. From thickness-dependent measurements, we determine the spin diffusion length in a single Pt film to be 11±3 nm, which is significantly larger compared to that of Pt adjacent to a magnetic layer.

show abstract

mentioning

confidence: 78%

Section: Adjacent Fmmentioning

confidence: 93%

mentioning

confidence: 99%

See 1 more Smart Citation

Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films

et al. 2017

View full text Add to dashboard Cite

show abstract

“…In addition, Elezzabi et al [24] developed a time-resolved optical technique to directly measure the spin relaxation process in Au to be τ s,Au = (45 ± 5) ps. However, this method is not suitable for heavy metals such as Pt, Ta and W with short τ s [25]. Recently, Dyakonov [26] theoretically, then Vélez et al [27] and Wu et al [28] experimentally demonstrated a so-called Hanle magnetoresistance (MR) effect in Pt and Ta: a spin accumulation at the sample boundaries caused by the spin Hall effect is dephased by a magnetic field via the Hanle effect, which results in an additional positive MR.…”

mentioning

confidence: 99%

Determination of spin relaxation times in heavy metals via second-harmonic spin injection magnetoresistance

et al. 2017

View full text Add to dashboard Cite

In tunnel junctions between ferromagnets and heavy elements with strong spin orbit coupling the magnetoresistance is often dominated by tunneling anisotropic magnetoresistance (TAMR). This makes conventional DC spin injection techniques impractical for determining the spin relaxation time (τs). Here, we show that this obstacle for measurements of τs can be overcome by 2nd harmonic spin-injection-magnetoresistance (SIMR). In the 2nd harmonic signal the SIMR is comparable in magnitude to TAMR, thus enabling Hanle-induced SIMR as a powerful tool to directly determine τs. Using this approach we determined the spin relaxation time of Pt and Ta and their temperature dependences. The spin relaxation in Pt seems to be governed by Elliott-Yafet mechanism due to a constant resistivity×spin relaxation time product over a wide temperature range.PACS numbers: 72.25. Rb, 72.25.Ba, 73.50.Bk, 73.40.Rw The large applied potential of spin-orbit-torques for magnetic random access memory has stimulated intensive interest in investigating spin orbit coupling (SOC) in heavy metals such as Pt and Ta [1][2][3][4][5][6][7][8][9][10][11]. Their spin Hall angle (θ SH ), spin diffusion length (l s ) and spin relaxation time (τ s ), which influence switching efficiency are important parameters for determining their effectiveness, but especially the latter two are experimentally hard to assess. Accurate determination of τ s could also help to identify the spin relaxation mechanisms [12]. Though θ SH and l s have been measured by spin pumping [13][14][15][16][17] In fact, spin injection experiments in nonlocal spin valves [29][30][31][32][33][34][35] and 3-terminal geometries [36][37][38][39][40] are both powerful tools in measuring τ s in metals and semiconductors. In these experiments, ferromagnetic layer (FM)/tunnel barrier/nonmagnetic layer (NM) junctions are adopted to both inject a non-equilibrium spin accumulation and simultaneously determine their magnitude. These measurement were used to determine spin relaxation times in a wide variety of materials, e.g., τ s,Si =55 -285 ps for heavily doped silicon [40]; τ s,Graphene > 1 ns for graphene/BN [41]; τ s,Al =110 ps for aluminum [29], τ s,Cu =22 ps for copper [42] and τ s,Au =45 ps for gold [32].However, it is impractical to apply these spin injection experiments to measure τ s in heavy metals with strong SOC for at least two reasons. First, l s in this case is so short (about several nanometers) that the preparation of nonlocal spin valves with comparable dimensions is beyond current lithography capabilities. Second, the real contact resistance is r = r C + r SI , where r SI and r C are the contact resistance induced by spin injection (SI) and the original contact resistance without r SI , respectively. Here r SI equals to r N r C /(r N +r C ) and the spin resistance in the NM layer r N is defined as ρ N l sN . ρ N and l sN are the resistivity and spin relaxation length of NM, respectively. For this discussion we ignore the influence of spin resistance in FM on r SI due to...

show abstract

“…In our work here, we study optical and magneto-optical (MO) properties of the modulated Fe-Pt multilayer metamaterials by means of ellipsometry, namely generalized MO ellipsometry (GME) [33,34], at several wavelengths in the visible and near-infrared region. GME's main advantage is the ability to investigate complex MO parameters with unprecedented precision, since it allows one to determine optical and MO properties simultaneously [33][34][35][36][37][38][39]. In addition, the dispersion of the parameters can be obtained through spectroscopic GME measurements [40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Magneto-Optical Activities of Modulated Fe - Pt Multilayer Metamaterials

et al. 2019

Self Cite

View full text Add to dashboard Cite

We study optical and magneto-optical (MO) properties of epitaxially grown modulated Fe-Pt multilayer metamaterials by means of generalized MO ellipsometry (GME). Large Kerr rotation, ellipticity, and MO coupling parameters in the visible and near-infrared regions are obtained for modulated metamaterials, in which the stacking sequences follow an inverse Fibonacci series. In contrast, periodic multilayers show small MO parameters, although they otherwise exhibit magnetic and optical properties that are very similar to those for the modulated metamaterials. The present study demonstrates that specific thickness modulation can have a significant materials design potential for one-dimensional magnetic metamaterials.

show abstract

Absence of detectable current-induced magneto-optical Kerr effects in Pt, Ta, and W

Cited by 24 publications

References 41 publications

Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films

Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films

Determination of spin relaxation times in heavy metals via second-harmonic spin injection magnetoresistance

Enhanced Magneto-Optical Activities of Modulated Fe - Pt Multilayer Metamaterials

Contact Info

Product

Resources

About