Effective exchange interaction for terahertz spin waves in iron layers

Abstract

The exchange stiffness is a central material parameter of all ferromagnetic materials. Its value controls the Curie temperature as well as the dynamic properties of spin waves to a large extend. Using ultrashort spin current pulses we excite perpendicular standing spin waves (PSSW) in ultrathin epitaxial iron layers at frequencies of up to 2.4 THz. Our analysis shows that for the PSSWs the observed exchange stiffness of iron is about 20% smaller compared to the established iron bulk value. In addition, we find an interface-related reduction of the effective exchange stiffness for layers with the thickness below 10 nm. To understand and discuss the possible mechanisms of the exchange stiffness reduction we develop an analytical 1D-model. In doing so we find that the interface induced reduction of the exchange stiffness is mode-dependent.

References in corpus (15)

• Anatomy of Spin-Transfer Torque
• First-principles investigation of the very large Perpendicular Magnetic Anisotropy at Fe|MgO Interfaces
• Ab-initio calculations of exchange interactions, spin-wave stiffness constants, and Curie temperatures of Fe, Co, and Ni
• Ultrafast transport of laser-excited spin polarized carriers in Au/Fe/MgO(001)
• Damping by slow relaxing rare earth impurities in Ni80Fe20
• Nanoscale confinement of ultrafast spin transfer torque exciting non-uniform spin dynamics by femtosecond spin current pulses
• Inverse Spin Hall Effect in NiFe / Normal Metal Bilayers
• Anatomy of perpendicular magnetic anisotropy in Fe/MgO magnetic tunnel junctions: First principles insight
• Femtosecond spin current pulses generated by the non-thermal spin-dependent Seebeck effect and interacting with ferromagnets in spin valves
• An ab initio effective Hamiltonian for magnetism including longitudinal spin fluctuations
• Absorption and generation of femtosecond laser-pulse excited spin currents in non-collinear magnetic bilayers
• Extended spin model in atomistic simulations of alloys
• High-frequency magnon excitation due to femtosecond spin-transfer torques
• Micromagnetic view on ultrafast magnon generation by femtosecond spin current pulses
• Assessing different approaches to ab initio calculations of spin wave stiffness

Cited by in corpus (6)

• Accessing ultrafast spin-transport dynamics in copper using broadband terahertz spectroscopy
• Hybrid magnon-phonon cavity for large-amplitude terahertz spin-wave excitation
• Exploring terahertz-scale exchange resonances in synthetic ferrimagnets with ultrashort optically induced spin currents
• Finite-frequency spin conductance of a ferro-/ferrimagnetic-insulator|normal-metal interface
• Multiscale approach for modeling magnetization properties of inhomogeneous ultrathin magnetic layers
• Control of ultrashort spin current pulses in metallic multilayers