arXiv subjects

R. Hauptmann

Publications and source records attributed to R. Hauptmann.

4 recordsLinked to original sources

arXiv1998

Magnetic bound states in the quarter-filled ladder system $α'-NaV_{2}O_{5}$}

Raman scattering in the quarter-filled spin ladder system alpha'-NaV_2O_5 shows in the dimerized singlet ground state ($T \leq T_{SP}=35K$) an unexpected sequence of three magnetic bound states. Our results suggest that the recently proposed mapping onto an effective spin chain for $T > T_{SP}$ has to be given up in favor of the full topology and exchange paths of a ladder in the dimerized phase for $T < T_{SP}$. As the new ground state we propose a dynamic superposition of energetically nearly degenerate dimer configurations on the ladder.

cond-mat.str-el↗

arXiv1997

Magnetic Resonance in the Spin-Peierls compound $α'-NaV_2O_5$

We present results from magnetic resonance measurements for 75-350 GHz in $α$'-NaV$_{2}$O$_{5}$. The temperature dependence of the integrated intensity indicates that we observe transitions in the excited state. A quantitative description gives resonances in the triplet state at high symmetry points of the excitation spectrum of this Spin-Peierls compound. This energy has the same temperature dependence as the Spin-Peierls gap. Similarities and differences with the other inorganic compound CuGeO$_{3}$ are discussed.

cond-mat↗

arXiv1997

Interference of a first-order transition with the formation of a spin-Peierls state in alpha'-NaV2O5?

We present results of high-resolution thermal-expansion and specific-heat measurements on single crystalline alpha'-NaV2O5. We find clear evidence for two almost degenerate phase transitions associated with the formation of the dimerized state around 33K: A sharp first-order transition at T1=(33+-0.1)K slightly below the onset of a second-order transition at T2onset around (34+-0.1)K. The latter is accompanied by pronounced spontaneous strains. Our results are consistent with a structural transformation at T1 induced by the incipient spin-Peierls (SP) order parameter above T2=TSP.

cond-mat↗

arXiv1997

Experimental evidence for a spin-Peierls-transition in $α'-NaV_2O_5$

We present the first measurements of magnetisation and Raman light scattering on $α'-NaV_2O_5$ single crystals. Below 34 K, we observe a pronounced isotropic decrease of the susceptibility indicating the opening of a spin gap. The transition temperature is slightly field dependent. Raman experiments reveal a crystallographic distortion at the transition. Our results clearly establish $α'-NaV_2O_5$ to be the second inorganic spin-Peierls system.

cond-mat.str-el↗