TY - JOUR
T1 - Bridging frustrated-spin-chain and spin-ladder physics
T2 - Quasi-one-dimensional magnetism of BiCu2PO6
AU - Tsirlin, Alexander A.
AU - Rousochatzakis, Ioannis
AU - Kasinathan, Deepa
AU - Janson, Oleg
AU - Nath, Ramesh
AU - Weickert, Franziska
AU - Geibel, Christoph
AU - Läuchli, Andreas M.
AU - Rosner, Helge
N1 - Publisher Copyright:
© 2010 The American Physical Society.
PY - 2010
Y1 - 2010
N2 - We derive and investigate the microscopic model of the quantum magnet BiCu2PO6 using band-structure calculations, magnetic susceptibility and high-field magnetization measurements, as well as exact diagonalization (ED) and density-matrix renormalization group (DMRG) techniques. The resulting quasi-one-dimensional spin model is a two-leg antiferromagnetic ladder with frustrating next-nearest-neighbor couplings along the legs. The individual couplings are estimated from band-structure calculations and by fitting the magnetic susceptibility with theoretical predictions, obtained using full diagonalizations. The nearest-neighbor leg coupling J1, the rung coupling J4, and one of the next-nearest-neighbor couplings J2 amount to 120-150 K while the second next-nearest-neighbor coupling is J2 (J2 /2. The spin ladders do not match the structural chains, and although the next-nearest-neighbor interactions J2 and J2( have very similar superexchange pathways, they differ substantially in magnitude due to a tiny difference in the O-O distances and in the arrangement of nonmagnetic PO4 tetrahedra. An extensive ED study of the proposed model provides the low-energy excitation spectrum and shows that the system is in the strong rung coupling regime. The strong frustration by the next-nearest-neighbor couplings leads to a triplon branch with an incommensurate minimum. This is further corroborated by a strong-coupling expansion up to second order in the inter-rung coupling. Based on high-field magnetization measurements, we estimate the spin gap of (32 K and suggest the likely presence of antisymmetric Dzyaloshinskii-Moriya anisotropy and interladder coupling J3. We also provide a tentative description of the physics of BiCu2PO6 in magnetic field, in the light of the low-energy excitation spectra and numerical calculations based on ED and DMRG. In particular, we raise the possibility for a rich interplay between one- and two-component Luttinger liquid phases and a magnetization plateau at 1/2 of the saturation value.
AB - We derive and investigate the microscopic model of the quantum magnet BiCu2PO6 using band-structure calculations, magnetic susceptibility and high-field magnetization measurements, as well as exact diagonalization (ED) and density-matrix renormalization group (DMRG) techniques. The resulting quasi-one-dimensional spin model is a two-leg antiferromagnetic ladder with frustrating next-nearest-neighbor couplings along the legs. The individual couplings are estimated from band-structure calculations and by fitting the magnetic susceptibility with theoretical predictions, obtained using full diagonalizations. The nearest-neighbor leg coupling J1, the rung coupling J4, and one of the next-nearest-neighbor couplings J2 amount to 120-150 K while the second next-nearest-neighbor coupling is J2 (J2 /2. The spin ladders do not match the structural chains, and although the next-nearest-neighbor interactions J2 and J2( have very similar superexchange pathways, they differ substantially in magnitude due to a tiny difference in the O-O distances and in the arrangement of nonmagnetic PO4 tetrahedra. An extensive ED study of the proposed model provides the low-energy excitation spectrum and shows that the system is in the strong rung coupling regime. The strong frustration by the next-nearest-neighbor couplings leads to a triplon branch with an incommensurate minimum. This is further corroborated by a strong-coupling expansion up to second order in the inter-rung coupling. Based on high-field magnetization measurements, we estimate the spin gap of (32 K and suggest the likely presence of antisymmetric Dzyaloshinskii-Moriya anisotropy and interladder coupling J3. We also provide a tentative description of the physics of BiCu2PO6 in magnetic field, in the light of the low-energy excitation spectra and numerical calculations based on ED and DMRG. In particular, we raise the possibility for a rich interplay between one- and two-component Luttinger liquid phases and a magnetization plateau at 1/2 of the saturation value.
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U2 - 10.1103/PhysRevB.82.144426
DO - 10.1103/PhysRevB.82.144426
M3 - Article
AN - SCOPUS:79961089603
SN - 1098-0121
VL - 82
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 14
M1 - 144426
ER -