Tunable damping, saturation magnetization, and exchange stiffness of half-Heusler NiMnSb thin films

Dürrenfeld, Philipp; Gerhard, F.; Chico, Jonathan; Dumas, Randy K.; Ranjbar, Mahdy; Bergman, Anders; Bergqvist, Lars; Delin, Anna; Gould, C.; Molenkamp, Laurens W.; Åkerman, Johan

doi:10.1103/physrevb.92.214424

Cited by 58 publications

(47 citation statements)

References 54 publications

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“…For LSMO single-layer films we find α = (0.9 ± 0.2)×10 −3 , which is on the same order as previous reports of LSMO thin films [21][22][23]26 . This low damping is also comparable to the values reported in Heusler alloy thin films 45,46 and may arise from LSMO can thus be an efficient source of spin current generated resonantly by microwave excitation. With a few-nanometer thick overlayer of SRO, α increases to ≈2×10 −3 ( Fig.…”

Section: Out-of-plane Fmr and Estimation Of Spin Transport Paramsupporting

confidence: 66%

Spin transport and dynamics in all-oxide perovskite La2/3Sr1/3MnO3/SrRuO3

et al. 2016

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Thin films of perovskite oxides offer the possibility of combining emerging concepts of strongly correlated electron phenomena and spin current in magnetic devices. However, spin transport and magnetization dynamics in these complex oxide materials are not well understood. Here, we experimentally quantify spin transport parameters and magnetization damping in epitaxial perovskite ferromagnet/paramagnet bilayers of La 2/3 Sr 1/3 MnO3/SrRuO3 (LSMO/SRO) by broadband ferromagnetic resonance spectroscopy. From the SRO thickness dependence of Gilbert damping, we estimate a short spin diffusion length of < ∼ 1 nm in SRO and an interfacial spin-mixing conductance comparable to other ferromagnet/paramagnetic-metal bilayers. Moreover, we find that anisotropic non-Gilbert damping due to two-magnon scattering also increases with the addition of SRO. Our results demonstrate LSMO/SRO as a spin-source/spin-sink system that may be a foundation for examining spin-current transport in various perovskite heterostructures.

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Section: Out-of-plane Fmr and Estimation Of Spin Transport Paramsupporting

confidence: 66%

Spin transport and dynamics in all-oxide perovskite La2/3Sr1/3MnO3/SrRuO3

et al. 2016

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“…Recently, there have been an increasing attention for finding metallic materials with small intrinsic damping, for instance half metallic Heusler materials and FeCo alloys 32,49 . Controlling and varying the magnetodynamical properties in these systems through doping or by other means, like defects, are very relevant and left for a future study.…”

Section: Discussionmentioning

confidence: 99%

Systematic study of magnetodynamic properties at finite temperatures in doped permalloy from first-principles calculations

et al. 2016

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By means of first principles calculations, we have systematically investigated how the magnetodynamic properties Gilbert damping, magnetization and exchange stiffness are affected when permalloy (Py) (Fe0.19Ni0.81) is doped with 4d or 5d transition metal impurities. We find that the trends in the Gilbert damping can be understood from relatively few basic parameters such as the density of states at the Fermi level, the spin-orbit coupling and the impurity concentration. The temperature dependence of the Gilbert damping is found to be very weak which we relate to the lack of intraband transitions in alloys. Doping with 4d elements has no major impact on the studied Gilbert damping, apart from diluting the host. However, the 5d elements have a profound effect on the damping and allows it to be tuned over a large interval while maintaining the magnetization and exchange stiffness. As regards spin stiffness, doping with early transition metals results in considerable softening, whereas late transition metals have a minor impact. Our result agree well with earlier calculations where available. In comparison to experiments, the computed Gilbert damping appears slightly underestimated while the spin stiffness show good general agreement.

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“…Although such values have yet to be realized, damping parameters as low as 0.001 have been reported for Co 2 FeAl 18 and NiMnSb 19 . However, Heusler alloys have non-trivial fabrication constraints, such as high-temperature annealing, which are also incompatible with spintronic and CMOS device fabrication constraints.…”

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confidence: 99%

Ultra-low magnetic damping of a metallic ferromagnet

et al. 2016

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Magnetic damping is of critical importance for devices that seek to exploit the electronic spin degree of freedom, as damping strongly a ects the energy required and speed at which a device can operate. However, theory has struggled to quantitatively predict the damping, even in common ferromagnetic materials 1-3 . This presents a challenge for a broad range of applications in spintronics 4 and spin-orbitronics that depend on materials and structures with ultra-low damping 5,6 . It is believed that achieving ultra-low damping in metallic ferromagnets is limited by the scattering of magnons by the conduction electrons. However, we report on a binary alloy of cobalt and iron that overcomes this obstacle and exhibits a damping parameter approaching 10 −4 , which is comparable to values reported only for ferrimagnetic insulators 7,8 . We explain this phenomenon by a unique feature of the band structure in this system: the density of states exhibits a sharp minimum at the Fermi level at the same alloy concentration at which the minimum in the magnetic damping is found. This discovery provides both a significant fundamental understanding of damping mechanisms and a test of the theoretical predictions proposed by Mankovsky and colleagues 3 .In recent decades, several theoretical approaches have attempted to quantitatively predict magnetic damping in metallic systems. One of the early promising theories was that of Kambersky, who introduced the so-called breathing Fermi-surface model 9-11 . More recently, Gilmore and Stiles 2 as well as Thonig et al. 12 demonstrated a generalized torque correlation model that includes both intraband (conductivity-like) and interband (resistivity-like) transitions. The use of scattering theory to describe damping was later applied by Brataas et al. 13 and Liu et al. 14 to describe damping in transition metals. A numerical realization of a linear response damping model was implemented by Mankovsky 3 for Ni-Co, Ni-Fe, Fe-V and Co-Fe alloys. For the Co-Fe alloy, these calculations predict a minimum intrinsic damping of α int ≈ 0.0005 at a Co-concentration of 10% to 20%, but was not experimentally observed 15 .Underlying this theoretical work is the goal of achieving new systems with ultra-low damping that are required in many magnonic and spin-orbitronics applications 7,8 . Ferrimagnetic insulators such as yttrium-iron-garnet (YIG) have long been the workhorse for these investigations, because YIG films as thin as 25 nm have experimental damping parameters as low as 0.9 × 10 −4 (ref. 16). Such ultra-low damping can be achieved in insulating ferrimagnets in part due to the absence of conduction electrons-and, therefore, the suppression of magnon-electron scattering. However, insulators cannot be used in most spintronic and spin-orbitronic applications, where a charge current through the magnetic material is required, nor is the requirement of growth on gadolinium gallium garnet templates compatible with spintronics and complementary metal-oxide semiconductor (CMOS) fabrication processes. One...

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Tunable damping, saturation magnetization, and exchange stiffness of half-Heusler NiMnSb thin films

Cited by 58 publications

References 54 publications

Spin transport and dynamics in all-oxide perovskite La2/3Sr1/3MnO3/SrRuO3

Spin transport and dynamics in all-oxide perovskite La2/3Sr1/3MnO3/SrRuO3

Systematic study of magnetodynamic properties at finite temperatures in doped permalloy from first-principles calculations

Ultra-low magnetic damping of a metallic ferromagnet

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