P5 Effective Models for Spin Systems

The aim of this project is to systematically derive effective models by continuous unitary transformations (CUTs) which describe the energetically low-lying excitations in terms of few quasiparticles or a low density of them. Thereby, the original problem can be significantly simplified. This has been shown extensively for spin ladders where the effective model is formulated in terms of triplons (elementary triplet excitations). Recently, the description of quasi-particle breakdown and the concomitant vanishing of the resonance line has been studied conceptually and for IPA-CuCl3 in particular. The CUTs used are suitable for gapped spin dimer systems with or without frustration in any dimension. Coupled spin ladders also describe quasi higher-dimensional systems.

This project lead to the follow-up project FP1 (Kai P. Schmidt).

Students in charge: Frederik Keim, Dr. Benedikt Fauseweh



B. Fauseweh, F. Groitl, T. Keller, K. Rolfs, D. A. Tennant, K. Habicht, and G. S. Uhrig, Time-dependent correlations in quantum magnets at finite temperature, Phys. Rev. B 94, 180404 (2016), open access version: arXiv:1607.04417

L. Splinter, N. A. Drescher, H. Krull, and G. S. Uhrig, Minimal model for the frustrated spin ladder system BiCu2PO6, Phys. Rev. B 94, 155115 (2016)

Benedikt Fauseweh, Dynamic Correlations in One-Dimensional Quantum Magnets at Finite Temperature - A Diagrammatic Approach, Dissertation 2016, TU Dortmund

E.S. Klyushina, A.C. Tiegel, B. Fauseweh, A.T.M.N. Islam, J.T. Park, B. Klemke, A. Honecker, G.S. Uhrig, S.R. Manmana, B. Lake, Magnetic excitations in the S = 1/2 antiferromagnetic-ferromagnetic chain compound BaCu2V2O8 at zero and finite temperature, Phys. Rev. B 93, 241109(R) (2016), open access version: arXiv:1602.06184

M. Hafez Torbati and G.S. Uhrig, Orientational bond and Néel order in the two-dimensional ionic Hubbard model, Physical Review B 93, 195128 (2016)

C.H. Redder and G. S. Uhrig, Topologically non-trivial Hofstadter bands on the kagome lattice, Physical Review A 93, 033654 (2016)

G.S. Uhrig, Tunable and direction-dependent group velocities in topologically protected edge states, Physical Review B 93, 205438 (2016)


B. Fauseweh and G. S. Uhrig, Finite temperature line shapes of multi-flavored hardcore bosons by the Brückner approach Physical Review B 92, 214417 (2015), open access version: arXiv:1507.03793

M. Powalski, G.S. Uhrig, K.P. Schmidt, Roton minimum as fingerprint of magnon-Higgs scattering in ordered quantum antiferromagnets, Phys. Rev. Lett. 115, 207202 (2015), open access version: arXiv:1504.07371

F. Keim and G.S. Uhrig, Effective One-Dimensional Models from Matrix Product States, Eur. Phys. J. B 88,154 (2015), open access version: arXiv:1503.02616

K. Coester, S. Clever, F. Herbst, S. Capponi, K. P. Schmidt A generalized perspective on non-perturbative linked cluster expansions, Europhys. Lett. 110, 20006 (2015), open access version: arXiv:1409.5007

D. G. Joshi, K. Coester, K. P. Schmidt, and M. Vojta, Non-linear bond-operator theory and 1/d expansion for coupled-dimer magnets, I. Paramagnetic phase, Phys. Rev. B 91, 094404 (2015), open access version: arXiv:1407.7870

M. Hafez Torbati, N. A. Drescher, G.S. Uhrig, From Gapped Excitons to Gapless Triplons in One Dimension, Eur. Phys. J. B 88, 36 (2015), open access version: arXiv:1408.3131

J. Krones and G. S. Uhrig, Effective models for Anderson impurity and Kondo problems from continuous unitary transformations, Phys. Rev. B 91, 125102 (2015), open access version: cond-mat arXiv:1412.8176


M. Hafez Torbati, N.A. Drescher, and G.S. Uhrig, Dispersive Excitations in the One-Dimensional Ionic Hubbard Model, Phys. Rev. B 89, 245126 (2014), open access version: arXiv:1403.2405

B. Fauseweh, J. Stolze, and G.S. Uhrig, Finite-temperature line shapes of hard-core bosons in quantum magnets: A diagrammatic approach tested in one dimension, Phys. Rev. B 90, 024428 (2014), open access version: arXiv:1402.4359


M. Powalski, K. Coester, R. Moessner, and K. P. Schmidt, Disorder by disorder and flat bands in the kagome transverse field Ising model, Phys. Rev. B 87, 054404 (2013), open access version: arXiv:1212.0736

G.S. Uhrig and K. Majumdar, Varied perturbation theory for the dispersion dip in the two-dimensional Heisenberg quantum antiferromagnet, Eur. Phys. J. B 86, 282 (2013), open access version: arXiv:1302.6201

B. Fauseweh and G.S. Uhrig, Multi-Particle Spectral Properties in the Transverse Field Ising Model by Continuous Unitary Transformations Phys. Rev. B 87, 184406 (2013), open access version: arXiv:1302.023


Back to overview P1-P10