TY - JOUR

T1 - Phase diagrams and multicritical points in randomly mixed magnets. I. Mixed anisotropies

AU - Fishman, Shmuel

AU - Aharony, Amnon

PY - 1978

Y1 - 1978

N2 - The critical behavior of a quenched random alloy of two materials with competing anisotropies is studied by renormalization-group techniques. Averaging over the random variables yields a translationally invariant effective Hamiltonian, in which the m-component spin is replaced by a nm-component spin vector and the limit n0 is taken at the end of the calculation. The only physical stable fixed point is "decoupled," leading to a Hamiltonian which separates into two parts, each depending on m1 or m2=m-m1 spin components only, asymptotically close to criticality. This leads to breakdown of standard scaling in the vicinity of the multicritical point. The resulting phase diagram exhibits two critical lines, corresponding to ordering of only m1 (or m2) spin components, intersecting at an angle at a tetracritical point. The phases where only m1 or m2 components order are separated by an intermediate phase, where all components order. The effect of corrections to scaling on the shape of the critical lines in the vicinity of the tetracritical point is examined. Experiments on rare-earth alloys and layered materials are discussed.

AB - The critical behavior of a quenched random alloy of two materials with competing anisotropies is studied by renormalization-group techniques. Averaging over the random variables yields a translationally invariant effective Hamiltonian, in which the m-component spin is replaced by a nm-component spin vector and the limit n0 is taken at the end of the calculation. The only physical stable fixed point is "decoupled," leading to a Hamiltonian which separates into two parts, each depending on m1 or m2=m-m1 spin components only, asymptotically close to criticality. This leads to breakdown of standard scaling in the vicinity of the multicritical point. The resulting phase diagram exhibits two critical lines, corresponding to ordering of only m1 (or m2) spin components, intersecting at an angle at a tetracritical point. The phases where only m1 or m2 components order are separated by an intermediate phase, where all components order. The effect of corrections to scaling on the shape of the critical lines in the vicinity of the tetracritical point is examined. Experiments on rare-earth alloys and layered materials are discussed.

UR - http://www.scopus.com/inward/record.url?scp=0001208434&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.18.3507

DO - 10.1103/PhysRevB.18.3507

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AN - SCOPUS:0001208434

SN - 0163-1829

VL - 18

SP - 3507

EP - 3520

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

IS - 7

ER -