Thermally Driven Long Range Magnon Spin Currents in Yttrium Iron Garnet due to Intrinsic Spin Seebeck Effect

Abstract

The longitudinal spin Seebeck effect refers to the generation of a spin current when heat flows across a normal metal/magnetic insulator interface. Until recently, most explanations of the spin Seebeck effect use the interfacial temperature difference as the conversion mechanism between heat and spin fluxes. However, recent theoretical and experimental works claim that a magnon spin current is generated in the bulk of a magnetic insulator even in the absence of an interface. This is the so-called intrinsic spin Seebeck effect. Here, by utilizing a non-local spin Seebeck geometry, we provide additional evidence that the total magnon spin current in the ferrimagnetic insulator yttrium iron garnet (YIG) actually contains two distinct terms: one proportional to the gradient in the magnon chemical potential (pure magnon spin diffusion), and a second proportional to the gradient in magnon temperature ($\nabla T_m$). We observe two characteristic decay lengths for magnon spin currents in YIG with distinct temperature dependences: a temperature independent decay length of ~ 10 $\mu$m consistent with earlier measurements of pure ($\nabla T_m=0$) magnon spin diffusion, and a longer decay length ranging from about 20 $\mu$m around 250 K and exceeding 80 $\mu$m at 10 K. The coupled spin-heat transport processes are modeled using a finite element method revealing that the longer range magnon spin current is attributable to the intrinsic spin Seebeck effect ($\nabla T_m\ne 0$), whose length scale increases at lower temperatures in agreement with our experimental data.

arXiv comment13 pages, 4 figures, 1 table

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Cited by in corpus (20)

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• Electrical properties of single crystal Yttrium Iron Garnet ultra-thin films at high temperatures
• Spin Seebeck Effect: Sensitive Probe for Elementary Excitation, Spin Correlation, Transport, Magnetic Order, and Domains in Solids
• All-optical cryogenic thermometry based on NV centers in nanodiamonds
• Synthetic antiferromagnetic coupling between ultra-thin insulating garnets
• Criteria for accurate determination of the magnon relaxation length from the nonlocal spin Seebeck effect
• Enhanced magnon spin transport in NiFe${}_2$O${}_4$ thin films on a lattice-matched substrate
• Giant transition-state enhancement of quasiparticle spin-Hall effect in an exchange-spin-split superconductor detected by non-local magnon spin-transport
• Long lifetime of thermally-excited magnons in bulk yttrium iron garnet
• Differences in the magnon diffusion length for electrically and thermally driven magnon currents in Y${}_3$Fe${}_5$O${}_{12}$
• Transient response of spin Peltier effect revealed by lock-in thermoreflectance measurement
• Probing thermal magnon current mediated by coherent magnon via nitrogen-vacancy centers in diamond
• Nonlocal magnon spin transport in yttrium iron garnet with tantalum and platinum spin injection/detection electrodes
• Tuning the diffusion of magnon in Y3Fe5O12 by light excitation
• Absence of evidence of spin transport through amorphous Y${}_3$Fe${}_5$O${}_{12}$
• Short-range Thermal Magnon Diffusion in Magnetic Garnet
• Magnonics in collinear magnetic insulating systems
• Long-range spin transport on the surface of topological Dirac semimetal
• Spin Peltier effect and its length scale in Pt/YIG system at high temperatures
• Unconventional magnon transport in antiferromagnet NiPS${}_3$ induced by an anisotropic spin-flop transition