Experimental Studies of Condensed Magnetic Systems

本文利用交流磁化率X ′（w）和中子自旋回波技术，对最近发现的随机交换（REIM）和随机场（RNS）伊辛模型项中的不寻常动力学临界行为进行了广泛的研究。线性Xl（w）和非线性X 'nl（w）都将作为w的函数进行研究。从中子散射实验中可以得到更精确的静态临界指数。新颖的，磁密，Rdom系统将被制造和探测，希望找到一个纯粹的伊辛Rdom交叉行为的例子，使用双折射和电容技术。一种新的光吸收方法将被用来更好地理解非平衡场冷Rb 2态的畴结构的性质。在理想的伊辛体系铁锌氟体系中，在逾渗阈值附近，研究了REIM/RIMs到伊辛自旋玻璃行为的交叉。最后，他们将继续使用AFMR，叉指电容，FTIR和光谱学以及中子散射技术制备和研究铁氟2/锌氟2，锰氟2/锌氟2和铁氟2/钴氟2的外延反铁磁绝缘体和超晶格。他们希望观察到自旋驻波和新的不稳定模式，维度交叉，布里渊区的折叠和磁振子态密度的修改。这些综合研究应该在磁现象研究的前沿领域提供有价值的见解。

An extensive investigation is proposed of the recently uncovered unusual dynamic critical behavior in random exchange (REIM) and random field (RFIM) Ising model terms, using ac susceptibility X'(w) and neutron spin echo techniques. Both linear Xl(w) and nonlinear X'nl (w) will be investigated as a function of w. More precise values for the static critical exponents of the RFIM will be sought from neutron scattering experiments. Novel, magnetically dense, RFIM systems will be fabricated and probed in the hope of finding an example of pure Ising to RFIM crossover behavior, using birefringence and capacitance techniques. A new optical absorption method will be used to better understand the nature of the domain structure of the nonequilibrium, field- cooled RFIM state. The crossover form REIM/RFIM to Ising spin- glass behavior will be examined near the percolation threshold in the ideal Ising system ironxzinc1-xfluorine2. Lastly, they will continue the preparation and study of epitaxed antiferromagnetic insulators and superlattices of iron fluorine2/zinc fluorine2, manganese fluorine2/zinc fluorine2 and iron fluorine2/cobalt fluorine2 using AFMR, interdigital capacitance, FTIR and optical spectroscopy and neutron scattering techniques. They hope to observe standing spin wave and new instability modes, dimensionality crossover, folding of the Brillouin Zone and modification of the magnon density of states. These combined studies should provide valuable insights in areas at the forefront of research in magnetic phenomena.