Spin correlations and reentrant spin-glass behavior in amorphous Fe-Mn alloys: Statics

Journal Article · Tue Nov 01 04:00:00 EST 1983 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.28.5160· OSTI ID:5476521

Aeppli, G; Shapiro, S M; Birgeneau, R J; Chen, H S

Neutron scattering studies have been performed on amorphous (Fe/sub 1-x/Mn/sub x/)/sub 75/P/sub 16/B/sub 6/Al/sub 3/ alloys for several concentrations x bracketing the spin-glass-ferromagnetic multicritical point found from magnetization measurements. The amorphous structure factor has been measured to 4.0 A/sup -1/, and changes considerably for x near the multicritical concentration. For the most Mn-rich sample (x = 0.35), the small-angle scattering is well described by a single Lorentzian. The corresponding inverse ferromagnetic correlation length kappa remains nonzero (less than 0.04 A/sup -1/) at all temperatures. For x = 0.32, the Lorentzian scattering profile persists. As T is reduced, kappa decreases to a value indistinguishable from zero and subsequently increases, as it should for a ferromagnet which evolves into a reentrant spin-glass. For progressively smaller x, the scattering function at low temperatures shows increasing deviations from the Lorentzian form, and instead is consistent with a power law Q/sup -alpha/ with 2<..cap alpha..<3. These results are very similar to those found in other alloy series which display both ferromagnetic and spin-glass behavior. We argue that this power-law form of the spin correlations in the reentrant phase provides an important clue to the nature of the ferromagnet--spin-glass transition and the reentrant state itself. This leads us to a detailed heuristic model for the phase diagram and phase-transition behavior, including the reentrant phenomenon. The model is based on a decomposition, via the frustration mechanism, of spin systems with exchange interactions of random sign, into spin-glass-like and ferromagnetic networks.

• Research Organization: Brookhaven National Laboratory, Upton, New York 11973, and Bell Laboratories, Murray Hill, New Jersey 07974
• OSTI ID: 5476521
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 28:9; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals &amp; Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
AMORPHOUS STATE
BORON ALLOYS
COHERENT SCATTERING
CORRELATIONS
DIAGRAMS
DIFFRACTION
EXCHANGE INTERACTIONS
FERROMAGNETISM
INTERACTIONS
IRON ALLOYS
MAGNETISM
MANGANESE ALLOYS
NEUTRON DIFFRACTION
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PHOSPHORUS ADDITIONS
SCATTERING
SMALL ANGLE SCATTERING
SPIN GLASS STATE
STRUCTURE FACTORS