# Non-local magnon transconductance in extended magnetic insulating films.\\ Part I: spin diode effect

**Authors:** Ryuhei Kohno, Nicolas Thiery, Eric Clot, Richard Schlitz, Kyongmo An, Vladimir V. Naletov, Laurent Vila, Nathan Beaulieu, Jamal Ben Youssef, Hugo Merbouche, Vincent Cros, Madjid Anane, Thomas Hauet, Vladislav E. Demidov, Sergej O. Demokritov, Gregoire de Loubens, Olivier Klein  
**arXiv:** [2210.08304](https://arxiv.org/abs/2210.08304)  
**Date:** 2022-10-15  
**Summary page:** https://www.summarizepaper.com/en/paper/2210.08304v1/

## Key points

- Nonlinear transport properties of magnons in extended magnetic insulating films
- Focus on the spin diode effect
- Magnons emitted or absorbed through spin transfer effects via YIG|Pt interface
- Goal is to understand mechanisms behind asymmetric electrical variation of magnon transconductance
- Asymmetry driven by variation in density of low-lying spin excitations due to electrical shift of magnon chemical potential
- Three distinct regimes for transport properties of low-energy magnons:
- Ballistic regime at low currents, determined by film thickness
- Highly correlated regime limited by magnon-magnon relaxation processes near damping compensation threshold
- Diffusive transport regime dominated by scattering with high-energy magnons as temperature approaches Curie temperature under emitter
- Sequence of transport regimes analogous to electron hydrodynamic transport in ultra-pure media predicted by Radii Gurzhi
- Study complements Part II which investigates propagating magnons across entire spectrum

## Summary

This review focuses on the nonlinear transport properties of magnons in extended magnetic insulating films, specifically studying the spin diode effect. Magnons are electrically emitted or absorbed inside YIG films through spin transfer effects via a YIG$\vert$Pt interface. The goal of this study is to experimentally understand the underlying mechanisms behind the asymmetric electrical variation of magnon transconductance, which resembles an electric diode. The key factor driving this asymmetry is the variation in the density of low-lying spin excitations due to an electrical shift of the magnon chemical potential. As the intensity of spin transfer increases in the forward direction (magnon emission regime), the transport properties of low-energy magnons go through three distinct regimes. In the first regime, at low currents, where the spin current is a linear function of the electrical current, spin transport is ballistic and determined by the film thickness. In the second regime, for amplitudes approaching the damping compensation threshold, there is a transition to a highly correlated regime limited by magnon-magnon relaxation processes. This regime is characterized by a saturation of magnon transconductance. Here, thermal fluctuations beneath the emitter play a crucial role in controlling magnon density. In the third regime, as temperature under emitter approaches Curie temperature scattering with high-energy magnons dominates leading to diffusive transport. It is worth noting that this sequence of transport regimes bears analogy with electron hydrodynamic transport in ultra-pure media predicted by Radii Gurzhi. This study specifically focuses on exploring these transport regimes within low-energy part of magnon manifold and complements Part II (reference: kohno_2F) which concentrates on investigating and understanding propagating magnons across their entire spectrum providing valuable insights into understanding and manipulating nonlinear transport properties and spin dynamics in extended magnetic insulating films with potential applications in spintronics and magnon based devices.