| Scholar Profiles Sara Gamble2002 - 2003 University Scholar "During the time I have spent in and out of the classroom working on problem sets I have learned a great deal in the textbook sense about physics. I really wanted the chance to try to apply that knowledge in a practical laboratory setting. It is my hope that through the USP I will be afforded the opportunity to both see what the physics research community is like and hopefully contribute something to it." |
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Sara is a senior majoring in physics. She is the vice president of the UF chapter of the Society of Physics Students and volunteers for "Physics is Phun" shows in the community. She is an Anderson Scholar and a research fellow for the UF Center for Condensed Matter Sciences. She has participated in the UF Research Experience for Undergraduates and has presented a research paper at the annual meeting of the American Physics Society.
Research Description:Dielectric Properties of the S = 2 Haldane Gap Material MNCL3(C12H8N2) One of the most revolutionary ideas in the study of one-dimensional magnetic chain systems was proposed by Haldane when he theorized that, for integral quantum spin chains, an energy gap exists between the ground and first excited states. My project involves the study of the dielectric properties of the compound MnCl3(C12H8N2), a material that may belong to this category. For a typical Haldane gap material, the temperature dependence of the magnetic susceptibility, É"(T), will exhibit a Curie-like behavior at high temperatures, a broad maximum lower temperatures, and steep decline to zero as T approaches zero. For reasons currently not understood, MnCl3(phen) does not exhibit this behavior. The susceptibility data broadly peaks at 80K, significantly increases at 22K, and subsequently decreases in the low temperature limit. This jump in É"(T) at 22K indicates magnetic ordering, but is not indicative of the form associated with the canonical antiferromagnetism model. Further, this 22K magnetic alignment is anomalous because it is unaccompanied by a change in the specific heat of the material. My measurements explore this 22K anomaly. Specifically, I have been taking high sensitivity capacitance readings to measure the dielectric constant of the material as a function of temperature in order to determine if a structural transition takes place that would correlate with the magnetic data. The utilized apparatus consists of a copper parallel plate capacitor bolted to the base of a prefabricated cryogenic probe functional from 1.7 to 300K. An excitation voltage is sent through the sample, nulled through bridge balancing techniques, and subsequently returned to a lock-in amplifier. Deviations from the null indicate a transition is taking place. Preliminary results have indicated a change in the dielectric constant between 20 and 30K and I am now attempting to determine more precisely both the temperature and nature of the transition. |
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