Spin Chain in Magnetic Field: Limitations of the Large-N Mean-Field Theory

Journal Article · Sun Feb 01 00:00:00 EST 2015 · Acta Physica Polonica, Series A

DOI:https://doi.org/10.12693/APhysPolA.127.201· OSTI ID:1193711

Wohlfeld, K. ^[1]; Chen, Cheng-Chien ^[2]; van Veenendaal, M. ^[3]; Devereaux, T. P. ^[4]

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1. Univ. of Warsaw (Poland). Inst. of Theoretical Physics
2. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
3. Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics
4. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Inst. for Materials and Energy Sciences

Motivated by the recent success in describing the spin and orbital spectrum of a spin-orbital chain using a large-N mean-field approximation [Phys. Rev. B 91, 165102 (2015)], we apply the same formalism to the case of a spin chain in the external magnetic field. It occurs that in this case, which corresponds to N=2 in the approximation, the large-N mean-field theory cannot qualitatively reproduce the spin excitation spectra at high magnetic fields, which polarize more than 50% of the spins in the magnetic ground state. This, rather counterintuitively, shows that the physics of a spin chain can under some circumstances be regarded as more complex than the physics of a spin-orbital chain.

• Research Organization: SLAC National Accelerator Lab., Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); Polish National Science Centre (NCN)
• Grant/Contract Number: DE-AC02-76SF00515; DE-AC02-06CH11357; DE- FG02-03ER46097; AC02-76SF00515; AC02-06CH11357; FG02-03ER46097
• OSTI ID: 1193711
• Alternate ID(s): OSTI ID: 1222725
• Journal Information: Acta Physica Polonica, Series A, Vol. 127, Issue 2; ISSN 0587-4246
• Publisher: Jagiellonian University
• Country of Publication: United States
• Language: English

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