TY - JOUR

T1 - A study on composed nonextensive magnetic systems

AU - Navarro, F. A.R.

AU - Reis, M. S.

AU - Lenzi, E. K.

AU - Oliveira, I. S.

N1 - Funding Information:
F.A.R.N. and M.S.R. acknowledge the Brazilian Agencies CAPES and CNPq, respectively, for financial support.

PY - 2004/11/15

Y1 - 2004/11/15

N2 - We investigate the magnetic properties of a composed nonextensive system. The work is motivated by recent proposals that manganites are magnetically nonextensive objects, according to Tsalhs statistics. We consider a two-parts composed system, A-B (both spins 1/2), and calculate self-consistently the partial magnetizations in the mean field approximation, MA and M B, for the cases the coupling between the subsystems is either ferro or anti-ferromagnetic. This involves the notion of partial trace in the nonextensive statistics. For temperatures below the magnetic ordering temperatures, and q ≠ 1, we found strong disagreement between the M vs. T curves calculated from the total 4 × 4 Hubert space, through ρ q, when compared to the calculation made from the 2 × 2 subspaces, if we use the usual definition ρA(B) ≡ Tr B(A)(ρ), and then elevates the matrices to the qth power, as adopted in other contexts in the literature of the nonextensive statistics. On another hand, full agreement is found if we take ρA(B),q ≡ TrB(A)(ρq), remaining q an implicit parameter.

AB - We investigate the magnetic properties of a composed nonextensive system. The work is motivated by recent proposals that manganites are magnetically nonextensive objects, according to Tsalhs statistics. We consider a two-parts composed system, A-B (both spins 1/2), and calculate self-consistently the partial magnetizations in the mean field approximation, MA and M B, for the cases the coupling between the subsystems is either ferro or anti-ferromagnetic. This involves the notion of partial trace in the nonextensive statistics. For temperatures below the magnetic ordering temperatures, and q ≠ 1, we found strong disagreement between the M vs. T curves calculated from the total 4 × 4 Hubert space, through ρ q, when compared to the calculation made from the 2 × 2 subspaces, if we use the usual definition ρA(B) ≡ Tr B(A)(ρ), and then elevates the matrices to the qth power, as adopted in other contexts in the literature of the nonextensive statistics. On another hand, full agreement is found if we take ρA(B),q ≡ TrB(A)(ρq), remaining q an implicit parameter.

KW - Manganites

KW - Non-extensive statistics

KW - Partial trace

UR - http://www.scopus.com/inward/record.url?scp=4544230519&partnerID=8YFLogxK

U2 - 10.1016/j.physa.2004.05.074

DO - 10.1016/j.physa.2004.05.074

M3 - Artículo

AN - SCOPUS:4544230519

SN - 0378-4371

VL - 343

SP - 499

EP - 504

JO - Physica A: Statistical Mechanics and its Applications

JF - Physica A: Statistical Mechanics and its Applications

IS - 1-4

ER -