Ground state lost but degeneracy found: The effective thermodynamics of artificial spin ice

Physical Review Letters

Volumn 98, Issue 21, 2007, Pages

  Nisoli, Cristiano ^a   Wang, Ruifang ^a   Li, Jie ^a   McConville, William F ^a   Lammert, Paul E ^a   Schiffer, Peter ^a   Crespi, Vincent H ^a  

^a PENNSYLVANIA STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DEMAGNETIZATION; FERROMAGNETIC MATERIALS; GROUND STATE; ICE; MATHEMATICAL MODELS; THERMODYNAMIC PROPERTIES;

FERROMAGNETIC ISLANDS; MODEL SYSTEMS; SPIN ICE MATERIALS;

SPIN DYNAMICS;

EID: 34547341942     PISSN: 00319007     EISSN: 10797114     Source Type: Journal    
DOI: 10.1103/PhysRevLett.98.217203     Document Type: Article

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13. The field magnitude is reduced from 1280 Oe (well above the coercive field of an island) to 800 Oe in steps of 32 Oe, then to zero primarily in steps of 16 Oe, with a sweep rate of 24000Oe/s and a hold time of 1 s at each field value. The sample rotates at 1000 RPM. Increasing the hold time tenfold does not substantively change the results. The step size of 16 Oe is the maximal such value that successfully demagnetizes the sample. The magnetic moment of a single island, 80×220×25nm thick, is ∼3×107μB. Details are available in R.F. Wang, J. Li, W. McConville, C. Nisoli, X. Ke, J.W. Freeland, V. Rose, M. Grimsditsch, P. Lammert, V.H. Crespi, and P. Schiffer, J. Appl. Phys. 101, 09J104 (2007). JAPIAU 0021-8979 10.1063/1.2712528
14. Calculations using the Object Oriented MicroMagnetic Framework yield EIII-EII=0.67 and EIV-EII=3.4 in units of EII-EI, at a lattice constant of 320 nm (http://math.nist.gov/oommf).