TY - JOUR
T1 - H-T phase diagram for spin-glasses
T2 - An experimental study of Ag:Mn
AU - Chamberlin, R. V.
AU - Hardiman, M.
AU - Turkevich, L. A.
AU - Orbach, R.
PY - 1982
Y1 - 1982
N2 - We present high-resolution SQUID (superconducting quantum interference device) measurements of the dc magnetization on two Ag:Mn samples containing 2.6 and 4.0 at.% Mn. We have measured in detail the temperature dependence of the magnetization on warming through the glass temperature, TG, (i) after cooling to T<TG in a near-zero field and then applying the measurement field, zero-field cooled, and (ii) after cooling to T<TG in the measurement field. This has been done for fields 0.5H500 Oe. The temperature derivative, dM (H,T)dT, of the ZFC curve shows structure, allowing the identification of several characteristic temperatures associated with the paramagnetic to spin-glass transition in the presence of an external magnetic field. The temperature, TB, where the crossover from a Curie-like to a nonlinear susceptibility occurs, behaves as H0.5±0.1. Two further temperatures, T» and TP, where T»<TP<TG0(H'0) are suggested as possible candidates for the theoretical-field-dependent transition temperature TG(H) given by {1-[TG(H)TG0]}=Ah23 where h=HJ=g1/4BHkBTG0 and A is of order unity. We find {1-[T»(H)TG0]}=Bh0.70±0.05, but where B is approximately (19)2/3. However, the TP data are consistent with the theoretical prediction (A1) using no adjustable parameters, but the range of data is insufficient to enable an unambiguous verification of the theory. On the basis of recent theories, we suggest that the system entering the spin-glass phase at TG(H) should be marked experimentally by dc=MHstatic>ac(1/2,Hosc,Hstatic) where M is the magnetization, Hstatic the magnitude of the dc field, Hosc the amplitude of the ac oscillating field, and 1/2 its frequency. This argument leads us to conclude that TP(H) should be taken as the experimental definition of TG(H).
AB - We present high-resolution SQUID (superconducting quantum interference device) measurements of the dc magnetization on two Ag:Mn samples containing 2.6 and 4.0 at.% Mn. We have measured in detail the temperature dependence of the magnetization on warming through the glass temperature, TG, (i) after cooling to T<TG in a near-zero field and then applying the measurement field, zero-field cooled, and (ii) after cooling to T<TG in the measurement field. This has been done for fields 0.5H500 Oe. The temperature derivative, dM (H,T)dT, of the ZFC curve shows structure, allowing the identification of several characteristic temperatures associated with the paramagnetic to spin-glass transition in the presence of an external magnetic field. The temperature, TB, where the crossover from a Curie-like to a nonlinear susceptibility occurs, behaves as H0.5±0.1. Two further temperatures, T» and TP, where T»<TP<TG0(H'0) are suggested as possible candidates for the theoretical-field-dependent transition temperature TG(H) given by {1-[TG(H)TG0]}=Ah23 where h=HJ=g1/4BHkBTG0 and A is of order unity. We find {1-[T»(H)TG0]}=Bh0.70±0.05, but where B is approximately (19)2/3. However, the TP data are consistent with the theoretical prediction (A1) using no adjustable parameters, but the range of data is insufficient to enable an unambiguous verification of the theory. On the basis of recent theories, we suggest that the system entering the spin-glass phase at TG(H) should be marked experimentally by dc=MHstatic>ac(1/2,Hosc,Hstatic) where M is the magnetization, Hstatic the magnitude of the dc field, Hosc the amplitude of the ac oscillating field, and 1/2 its frequency. This argument leads us to conclude that TP(H) should be taken as the experimental definition of TG(H).
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U2 - 10.1103/PhysRevB.25.6720
DO - 10.1103/PhysRevB.25.6720
M3 - Article
AN - SCOPUS:0000970693
SN - 0163-1829
VL - 25
SP - 6720
EP - 6729
JO - Physical Review B
JF - Physical Review B
IS - 11
ER -