### Session D28: SPS Undergraduate Research II

2:30 PM–4:42 PM, Monday, March 15, 2010
Room: C124

Chair: Crystal Bailey, American Physical Society

Abstract ID: BAPS.2010.MAR.D28.3

### Abstract: D28.00003 : Magnetic Ordering in Yb$_{4}$LiGe$_{4}$

2:54 PM–3:06 PM

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#### Authors:

J.N. Svensson
(Boston College)

S. Disseler
(Boston College)

R.C. Johnson
(Boston College)

M.J. Graf
(Boston College)

S. Giblin
(ISIS Rutherford Appleton Laboratory)

P. Carretta
(Univ. of Pavia)

S. Peter
(Northwestern University)

R$_{5}$T$_{4}$ compounds (R = rare earth, T = Ge or Si) are interesting because the magnetic properties depend sensitively on changes in the crystalline structure. Yb$_{5}$Ge$_{4}$ such a compound, with (presumed) AFM order occurring at T$_{N}$ = 1.7 K. We are interested in the effects of substituting Li in place of one Yb atom. Previous measurements of the magnetic properties of polycrystalline Yb$_{4}$LiGe$_{4}$ using NMR, specific heat, and resistance measurements at temperatures down to 0.5 K and in magnetic fields up to 4 T were made for comparison with the parent compound. The resistance measurements showed a maximum at 1.1 K, which may indicate the onset of magnetic order. Thus we performed $\mu$SR measurements on Yb$_{4}$LiGe$_{4}$ and Yb$_{5}$Ge$_{4}$, and analysis of the data confirmed magnetic ordering (possibly AFM) at 1.1 K. $\mu$SR also revealed a dependence on the magnetic history of the sample. Currently we are studying the pressure dependence of the (presumed) T$_{N}$ to explore if increased pressure can drive the T$_{N}$ to 0 K, and results will be discussed.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.D28.3