Questioning Antiferromagnetic Ordering in the Expanded Metal, Li(NH3)4: A Lack of Evidence from μSR.

We present the results of a muon spin relaxation study of the solid phases of the expanded metal, Li(NH3)4. No discernible change in muon depolarization dynamics is witnessed in the lowest temperature phase (≤25 K) of Li(NH3)4, thus suggesting that the prevailing view of antiferromagnetic ordering is incorrect. This is consistent with the most recent neutron diffraction data. Discernible differences in muon behavior are reported for the highest temperature phase of Li(NH3)4 (82-89 K), attributed to the onset of structural dynamics prior to melting.

[1]  E. Zurek,et al.  Low energy structural dynamics and constrained libration of Li(NH3)4, the lowest melting point metal. , 2014, Chemical communications.

[2]  S. Giblin,et al.  Optimising a muon spectrometer for measurements at the ISIS pulsed muon source , 2014, 1404.4542.

[3]  R. Hoffmann,et al.  (Barely) solid Li(NH3)4: the electronics of an expanded metal. , 2011, Journal of the American Chemical Society.

[4]  R. Hoffmann,et al.  A molecular perspective on lithium-ammonia solutions. , 2009, Angewandte Chemie.

[5]  W. David,et al.  Structure and phase behavior of the expanded-metal compound 7Li(ND3)4. , 2009, Angewandte Chemie.

[6]  K. Papagelis,et al.  Magnetic ordering in the ammoniated alkali fullerides (NH3)K3−xRbxC60 (x = 2, 3) , 2007 .

[7]  N. Skipper,et al.  Proton dynamics in lithium-ammonia solutions and expanded metals. , 2006, The Journal of chemical physics.

[8]  A. Soper,et al.  Structural studies of ammonia and metallic lithium-ammonia solutions. , 2003, Journal of the American Chemical Society.

[9]  A. Shukla,et al.  Electronic interactions in the expanded metal compound Li-NH3. , 2002, Physical review letters.

[10]  Lejay,et al.  CeRu2: A magnetic superconductor with extremely small magnetic moments. , 1996, Physical Review B (Condensed Matter).

[11]  Fischer,et al.  Magnetism in RbC60 studied by muon-spin rotation. , 1995, Physical Review B (Condensed Matter).

[12]  Fischer,et al.  Evidence for endohedral muonium in Kx C60 and consequences for electronic structure. , 1992, Physical review letters.

[13]  J. Gibson,et al.  Low-temperature thermal effects in lithium/ammonia-d3 systems , 1984 .

[14]  T. R. White,et al.  Magnetic properties of metal-ammonia compounds , 1984 .

[15]  A. Stacy,et al.  Reevaluation of the crystal structure data on the expanded-metal compounds Li(NH/sub 3/)/sub 4/ and Li(ND/sub 3/)/sub 4/ , 1982 .

[16]  A. Stacy,et al.  Low temperature magnetic susceptibility of the expanded metal compounds Li(NH3)4, Li(ND3)4, and Li(CH3NH2)4 , 1982 .

[17]  P. Chieux,et al.  Neutron diffraction study and phase diagram investigation of the solid lithium-ammonia compound , 1975 .

[18]  M. Sienko,et al.  Low-temperature x-ray study of the compound tetraaminelithium(O) , 1968 .

[19]  J. Thompson,et al.  Phase Changes and Electrical Conductivity of Concentrated Lithium—Ammonia Solutions and the Solid Eutectic , 1965 .

[20]  J. Thompson,et al.  Hall effect, magnetoresistance, and thermoelectric power in lithium tetraammine , 1970 .