Resonant thermal energy transfer to magnons in a ferromagnetic nanolayer

Abstract

Energy harvesting is a concept which makes dissipated heat useful by transferring thermal energy to other excitations. Most of the existing principles are realized in systems which are heated continuously. We present the concept of high-frequency energy harvesting where the dissipated heat in a sample excites resonant magnons in a thin ferromagnetic metal layer. The sample is excited by femtosecond laser pulses with a repetition rate of 10 GHz, which results in temperature modulation at the same frequency with amplitude~0.1 K. The alternating temperature excites magnons in the ferromagnetic nanolayer which are detected by measuring the net magnetization precession. When the magnon frequency is brought onto resonance with the optical excitation, a 12-fold increase of the amplitude of precession indicates efficient resonant heat transfer from the lattice to coherent magnons. The demonstrated principle may be used for energy harvesting in various nanodevices operating at GHz and sub-THz frequency ranges.

Ultrafast magnetoacoustics in Galfenol nanostructures

“…In the applications considered above, laser sources with a high pulse repetition rate have excellent prospects. Resonant excitation of coherent magnons with phase and wavevector locking has been demonstrated using solid-state lasers with repetition rates of 1 and 10 GHz [94] , [95] . In turn, excitation of coherent phonons has been realized by means of a miniature semiconductor mode-locked laser with a repetition rate of 16 GHz [96] .…”

Large asymmetry in the magnetoresistance loops of ferromagnetic nanostrips induced by Surface Acoustic Waves

“…In an article published in parallel with the submission of this manuscript, Kobecki et al . 26 have proposed that the transfer of energy from phonons to magnetization precession can be used as energy harvesting by transferring thermal energy to other excitations. Our work shows that the transfer of energy can be sufficiently relevant to induce very visible effects in the AMR loop.…”

Сверхбыстрое Лазерно-Индуцированное Управление Магнитной Анизотропией Наноструктур

“…Шелухин, А.В. Щербаков в недавно выполненных экспериментах по оптическому возбуждению пленок галфенола толщиной несколько нанометров лазерными импульсами с частотой следования 10 GHz [140] модуляция температуры на 0.1 K приводила к возбуждению квазистационарной прецессии намагниченности при условии совпадения контролируемой магнитным полем частоты ферромагнитного резонанса и частоты следования лазерных импульсов или кратных ей гармоник. Амплитуда незатухающих гармонических осцилляций намагниченности в условии резонанса совпадает с амплитудой прецессии, достигаемой в экспериментах с объемными лазерными усилителями.…”