### Session T18: Focus Session: Low D/Frustrated Magnetism - Molecular Magnets II

2:30 PM–5:30 PM, Wednesday, March 23, 2011
Room: D172

Chair: M. Sarachik, City College of New York

Abstract ID: BAPS.2011.MAR.T18.8

### Abstract: T18.00008 : Experimental determination of the Weiss temperature of several variants of Mn12-ac

4:18 PM–4:30 PM

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#### Authors:

Shiqi Li
(CCNY \& GC-CUNY)

Lin Bo
(CCNY)

Bo Wen
(CCNY)

P. Subedi
(NYU)

Y. Yeshurun
(Bar-Ilan U., Israel)

A.D. Kent
(NYU)

M.P. Sarachik
(CCNY)

A.J. Millis
(Columbia U.)

C. Lampropoulos
(U. of Florida)

S. Mukherjee
(U. of Florida)

G. Christou
(U. of Florida)

We report measurements of the susceptibility in the temperature range from 3.5 K to 6.0 K of a series of Mn12-ac and Mn12-ac-MeOH samples in the shape of rectangular prisms. The susceptibility obeys a Curie-Weiss Law, where the temperature intercept varies systematically with sample aspect ratio. Using published demagnetization factors, we obtain the Curie-Weiss intercept for an infinitely long sample corresponding to intrinsic ordering temperatures Tc $\sim$ 0.85 K and $\sim$ 0.74 K for Mn12-ac and Mn12-ac-MeOH, respectively [1]. The difference in Tc for the two materials suggests an additional non-dipolar (exchange) contribution to the Weiss temperature that differs in the two materials because of the difference in ligand molecules. A similar comparison will also be reported for Mn12-toluate.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.T18.8