YBa2Cu3O6+δ的高频模及其随氧含量δ的变化

在中国原子能科学研究院新建的宽角(～30°)Be过滤探测器中子非弹性散射谱仪上,在入射中子能量从10直至150meV的范围内,测量了几种不同氧含量的YBa₂Cu₃O_6+δ样品的中子非弹性散射能谱。结果表明:(1)在δ=0和0.2时,在60至150meV能量范围内,发现有强的高频模存在,当其温度高到Nel点(～410K)以上直至466K时,没有观察出高频模强度的减弱。而δ=0.78和0.97时,在75至150meV能量范围内,散射强度在测量误 关键词：

HIGH FREQUENCY MODES OF YBa2Cu3O6+δ AND ITS VARLATIONS WITH OXYGEN CONTENT

Inelastic neutron scattering spectra of YBa₂Cu₃O_6+δ sample with several different oxygen contents δ have been obtained in the energy range from 10 to 150 meV at a new wide angle (～30°) Be-filter detecter spectrometer, CIAE,Beijing. The experiments show that :(l)For samples with δ=0 and δ=0.2, some strong high frequency modes appear in the energy range from ～60 to ～150 meV,and the intensity of modes does not decrease as the temperature is above Neel point until 466K. For samples with δ=0.78 and 0.97, however, the high frequency modes are not present and the scattering intensity spetra in the energe range from 70 to 150 meV seem to be a featureless background. (2)In the measured energe range from 10 to 150 meV the scattering intensities of sample with δ=0 and 0.2 is about two to three times as that of sample with δ = 0.78 and 0.97. (3) In the energe range below 60 meV, there are many distinct scattering peaks which are almost not shifted with δ, most of peaks are in a-greement with results of Renker and Parshin, and other peaks are observed for the first time. The strong dependence of high frequency modes and scattering intensities on the oxygen content δ would attribute to antiferromagnetics spin wave excitation.