TY - JOUR

T1 - Critical two- and three-spin correlations in EuS

T2 - An investigation with polarized neutrons

AU - Grigoriev, S. V.

AU - Metelev, S. V.

AU - Maleyev, S. V.

AU - Okorokov, A. I.

AU - Böni, P.

AU - Georgii, R.

AU - Lamago, D.

AU - Eckerlebe, H.

AU - Pranzas, K.

PY - 2005/12/1

Y1 - 2005/12/1

N2 - The critical magnetic scattering has been investigated in EuS by means of small-angle scattering with polarized neutrons using an inclined magnetic field geometry, allowing the determination of three-spin correlation functions. Two contributions to the critical magnetic scattering IΣ(q)=I↑(q) +I↓(q) and ΔI(q)=I↑(q)-I↓(q) were studied for temperatures near TC=16.52K. The I↑(q) and I↓(q) are the scattering intensities for the incident neutron beam polarized along (↑) and opposite (↓) to the magnetic field. The symmetric contribution, namely IΣ(q), comes from the pair-spin correlation function. The scattering intensity is well described by the Ornstein-Zernike expression IΣ(q)=A(q2+κ2)-1, where κ=ξ-1 is the inverse correlation length of the critical fluctuations. The correlation length ξ obeys the scaling law ξ=a0τ-ν, where τ=(T-TC) TC is the reduced temperature, a0=0.17nm, and ν=0.68±0. 01. The difference contribution ΔI(q) is caused by the three-spin chiral dynamical spin fluctuations that represent the asymmetric part of the polarization dependent scattering. The q dependence of ΔI(q) follows closely 1 q2. ΔI(q) depends on the temperature as τ-ν with ν=0.64±0.05. The exponents ν as determined by means of the static measurements by ξ and the dynamic measurements (using the chirality) are in excellent agreement with each other, demonstrating the internal consistency of the theory and the experiment. Therefore, our results confirm the principle of the critical factorization, which is known as Polyakov-Kadanoff-Wilson operator algebra.

AB - The critical magnetic scattering has been investigated in EuS by means of small-angle scattering with polarized neutrons using an inclined magnetic field geometry, allowing the determination of three-spin correlation functions. Two contributions to the critical magnetic scattering IΣ(q)=I↑(q) +I↓(q) and ΔI(q)=I↑(q)-I↓(q) were studied for temperatures near TC=16.52K. The I↑(q) and I↓(q) are the scattering intensities for the incident neutron beam polarized along (↑) and opposite (↓) to the magnetic field. The symmetric contribution, namely IΣ(q), comes from the pair-spin correlation function. The scattering intensity is well described by the Ornstein-Zernike expression IΣ(q)=A(q2+κ2)-1, where κ=ξ-1 is the inverse correlation length of the critical fluctuations. The correlation length ξ obeys the scaling law ξ=a0τ-ν, where τ=(T-TC) TC is the reduced temperature, a0=0.17nm, and ν=0.68±0. 01. The difference contribution ΔI(q) is caused by the three-spin chiral dynamical spin fluctuations that represent the asymmetric part of the polarization dependent scattering. The q dependence of ΔI(q) follows closely 1 q2. ΔI(q) depends on the temperature as τ-ν with ν=0.64±0.05. The exponents ν as determined by means of the static measurements by ξ and the dynamic measurements (using the chirality) are in excellent agreement with each other, demonstrating the internal consistency of the theory and the experiment. Therefore, our results confirm the principle of the critical factorization, which is known as Polyakov-Kadanoff-Wilson operator algebra.

UR - http://www.scopus.com/inward/record.url?scp=29844433600&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.72.214423

DO - 10.1103/PhysRevB.72.214423

M3 - Article

AN - SCOPUS:29844433600

VL - 72

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 21

M1 - 214423

ER -