Laser Spectroscopy of Fe-Co-Al-0 Granular Films

2005：1.我们用布里渊光散射(BLS)研究了溅射Co_&lt；51&gt；Al_&lt；18&gt；O_&lt；31&gt；薄膜中的超顺磁性(SPM)激发。我们可以观察到从0.5KoE以下无序态的重阻尼谱到4.5KoE以上场致铁磁态的静磁自旋波(SW)谱的瞬时行为。这是对SPM激发的第一次BLS观测。我们还证实了偶极耦合是激发频率的主要因素。我们有一个研究低温下SPM激发的计划。在室温下，我们研究了铁磁性薄膜Co_&lt；78&gt；Al_&lt；18&gt；O_&lt；18&gt；Co_&lt；66&gt；Al_&lt；11&gt；O_&lt；23&gt；和Co_&lt；63&gt；Al_&lt；13&gt；O_&lt；24&gt；在室温磁场下的磁常数，包括交换场H_t；ex&gt；。结合交换场和比电阻率，我们发现了电阻率ρ和交换率…之间的平方反比规律更多e字段H_&lt；ex&gt；：ρ_&lt；Co&gt；=22.1x H_&lt；ex&gt；^&lt；-2&gt；(μΩ.cm)。这里，H_&lt；ex&gt；是Koe单位。2006：我们认为平方反比定律是金属-非金属软磁颗粒薄膜的一种特征磁电性质。我们选择了Fe-Al-0薄膜作为另一种模型材料，并在室温下从SWS中测量了BLS。在本研究中，我们制备了Fe_&lt；83&gt；Al_&lt；19&gt；O_8，Fe_&lt；76&gt；12&gt；O_&lt；12&gt；，Fe_&lt；；Al_&lt；10&gt；O_&lt；17&gt；和Fe_&lt；62&gt；Al_&lt；19&gt；O_&lt；19&gt；同样，我们从SWS获得了BLS光谱，并确定了它们的频率作为磁场的函数。我们确定了Fe-Al-O薄膜的交换场，并证实了Fe-Al-O薄膜的ρ_&lt；Fe&gt；=30.3xH_&lt；ex&gt；^&lt；-2&gt；(μΩ·cm)。(1)我们已经清楚地证明了软铁磁性纳米颗粒薄膜中确实存在颗粒间交换耦合。(2)现在可以通过测量电阻率来确定Tm-Al-0(Tm=Fe，Co)颗粒膜的交换场常数。较少

2005 :1. We have examined superparamagnetic (SPM) excitations in a sputtered Co_<51>Al_<18>O_<31> film by Brillouin light scattering (BLS) at room temperature in magnetic fields of up to 6 kOe. We could observe transient behaviors from heavily damped spectra in disorder state below 0.5 kOe to the magnetostatic spin-wave (SW) spectra in the field-induced ferromagnetic state above 4.5 kOe. This is the very first BLS observation of the SPM excitations. We also confirmed that dipole coupling dominates the excitation frequencies. We have a plan to investigate the SPM excitations al low temperatures.2. We examined BLS from SWs in ferromagnetic Co_<78>Al_<18>O_<18>, Co_<66>Al_<11>O_<23> and Co_<63>Al_<13>O_<24> films in magnetic fields of up to 4.0 kOe at room temperature, and determined the magnetic constants including the exchange field H_<ex> for each film. Combining the exchange fields and the specific resistivities, we found an inverse-square law between the reisitivity ρ and the exchang … More e field H_<ex> : ρ_<Co>=22.1x H_<ex>^<-2> (μΩ.cm). Here, H_<ex> is in kOe unit.2006 :We consider that the inverse-square law is a characteristic magneto-electric property of the metal-nonmetal soft magnetic granular films. We selected Fe-Al-0 films as another model material, and measured BLS from the SWs at room temperature. We prepared Fe_<83>Al_<19>O_8, Fe_<76>Al_<12>O_<12>, Fe_<64>Al_<10>O_<17> and Fe_<62>Al_<19>O_<19> films in this study. Again, we obtained BLS spectra from SWs and determined their frequencies as a function of the magnetic field. We determined the exchange fields, and confirmed the inverse-square law given by ρ_<Fe>=30.3 x H_<ex>^<-2> (μΩ.cm) for the Fe-Al-O films.In this two years project we have obtained two important and quite new results. (1) We have clearly shown that inter-granule exchange coupling really exists in soft ferromagnetic nano-granular films. (2) Now it is possible to determine the exchange field constant of the TM-Al-0 (TM=Fe, Co) granular films through resistivity measurement. Less