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Condensed Matter Seminars

ics Condensed Matter
Thursday, March 20, 2008
4:00 PM
Physics Building, Room 204
Note special time.
Note special room.
Zhiqiang Mao [Host: Seunghun Lee]
Tulane University
"Fascinating Exotic Phenomena in Layered Ruthenates"
Perovskite ruthenates (Sr,Ca) n+1 Ru n O 3n+1 exhibit a rich variety of fascinating ordered ground states. Spin-triplet superconductivity, metamagnetic quantum criticality, itinerant ferromagnetism, antiferromagnetic Mott insulating, and half-metallic behavior were all found in close proximity to one another. These diverse ground states originate from the strong interplay of charge, spin, lattice, and orbital degrees of freedom. They offer a unique opportunity to tune the system and study the physics of novel quantum phases. In this talk, I will first give a brief overview on studies in this area, and then present our recent work on double layered ruthenates (Sr 1-x Ca x ) 3 Ru 2 O 7 (0 ≤ x ≤ 1). We have established a magnetic phase diagram for this system using the high quality single crystals grown by the floating-zone technique; this phase diagram exhibits significant new phenomena. We find a very unique magnetic state in close proximity to a two-dimensional ferromagnet with T c =0 K for 0.1 < x < 0.4. This state exhibits a surprisingly large Wilson ratio RW (e.g. R W ≈ 700 for x = 0.2); it freezes into a cluster glass (CG) at low temperatures. Furthermore, we observe evidence of non-Fermi liquid behavior as the frozen temperature of the CG phase approaches zero near x = 0.1. The origin of such a state will be discussed.

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