1996/10/23 by T. Lorenz, U. Ammerahl, T. Auweiler +3 · 2 citations
Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Cuprate #Diffraction #Field (mathematics) #Field dependence #Lattice (music) #Lattice constant #Magnetic field #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Scaling #Superconductivity #Theoretical and Computational Physics #cond-mat
paper · pdf · doi:10.1103/physrevb.55.5914
published as Phys. Rev. B 55, 5914 (1997) · 25 pages, 15 Figs., to appear in Phys. Rev. B55 (Vol.5)
arxiv created 1996/10/23 · openalex publication_date 1997/03/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present high-resolution measurements of the thermal-expansion coefficient and the magnetostriction along the a axis of CuGeO3 in magnetic fields up to 16 T. From the pronounced anomalies of the lattice constant a, occurring for both temperature- and field-induced phase transitions, clear structural differences between the uniform, dimerized, and incommensurate phases are established. A precise field temperature phase diagram is derived and compared in detail with existing theories. Although there is fair agreement with the calculations within the Cross-Fisher theory, some significant and systematic deviations are present. In addition, our data yield a high-resolution measurement of the field and temperature dependence of the spontaneous strain scaling with the spin-Peierls order parameter. Both the zero-temperature values as well as the critical behavior of the order parameter are nearly field independent in the dimerized phase. A spontaneous strain is also found in the incommensurate high-field phase, which is significantly smaller and shows a different critical behavior than that in the low-field phase. The analysis of the temperature dependence of the spontaneous strain yields a pronounced field dependence within the dimerized phase, whereas the temperature dependence of the incommensurate lattice modulation compares well with that of the dimerization in zero magnetic field.