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Pines, David Barzykin, Victor Vadimovich 2011-05-07T14:11:58Z 2011-05-07T14:11:58Z 10000-01-01 1995 This thesis consists of two parts, in which I consider two very different examples of magnetism in strongly correlated electron systems, the high-T$\sb{c}$ materials and heavy fermions. "In the first part, I study the magnetic properties of the high temperature superconductors, using both microscopic models and phenomenology based on the nuclear magnetic resonance and neutron scattering data. The resulting theory proposes a universal phase diagram of the magnetic behavior of the high temperature superconductors and related non-superconducting materials. While the overdoped materials exhibit nearly antiferromagnetic Fermi liquid behavior, for which the mean field description is appropriate, I show, on the basis of NMR experiments, that scaling develops in the underdoped metallic cuprate superconductors, once the antiferromagnetic correlation length exceeds a certain value, $\xi\sb{cr}\simeq2$. In the scaling regime, the value of the dynamical critical exponent is $z=1$, which is a consequence of spin waves present in the excitation spectrum. I show that the region of scaling on the phase diagram coinsides with the region of the so-called ""spin pseudogap"" behavior, which has been observed in many experiments." In the second part I consider the possible origin of small magnetic moment in some heavy fermion compounds. Apart from their heavy carrier mass, UPt$\sb3$ and URu$\sb2$Si$\sb2$ exhibit antiferromagnetic long range order with very small average values of magnetic moment, $\mu\sim0.01\mu\sb{B}$. I propose that such transitions are driven by an order parameter which is more complicated than that used for ordinary antiferromagnetism, and that the small antiferromagnetic moment appears as a second order effect as a result of the Dzyaloshinskii-Moriya-type interaction. In this thesis, I derive the complete symmetry classification of such states. I also propose methods of experimental verification of the symmetry of the order parameter. Made available in DSpace on 2011-05-07T14:11:58Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9543526.pdf: 4236392 bytes, checksum: 602cda6983faa26fb0ea6e6e4bd6c9c1 (MD5) Previous issue date: 1995 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:04:03Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:30:34-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9543526 (UMI)AAI9543526 http://hdl.handle.net/2142/23376 eng Copyright 1995 Barzykin, Victor Vadimovich Physics, Condensed Matter Magnetism in strongly correlated electron systems text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.