Browsing by Author "Abdel-Hafiez, M"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Low temperature thermodynamics of Yb6MoO12 and Lu6MoO12
    (Elsevier, 2019-03-25) Denisova, KN; Shlyakhtina, AV; Yumashev, O; Avdeev, M; Abdel-Hafiez, M; Volkova, OS; Vasiliev, AN
    We report on thermodynamic properties of both rhombohedral and cubic phases of Yb6MoO12-δ supplemented by measurements of Lu6MoO12-δ() magnetic properties. Among these series, Yb6MoO12-δ() only exhibits signatures of magnetic long-range order at TN∼2.5 K which is confirmed by both physical property measurements and neutron powder diffraction. Low temperature specific heat measured down to 100 mK suggests the rearrangement of magnetic subsystem at T* = 500 mK. © 2018 Elsevier B.V.
  • No Thumbnail Available
    Item
    Thermodynamic properties of the anisotropic frustrated spin-chain compound linarite PbCuSO4(OH)2
    (American Physical Society, 2013-11-15) Schäpers, M; Wolter, AUB; Drechsler, SL; Nishimoto, S; Müller, KH; Abdel-Hafiez, M; Schottenhamel, W; Büchner, B; Richter, J; Ouladdiaf, B; Uhlarz, M; Beyer, R; Skourski, Y; Wosnitza, J; Rule, KC; Ryll, H; Klemke, B; Kiefer, K; Reehuis, M; Willenberg, B; Süllow, S
    We present a comprehensive macroscopic thermodynamic study of the quasi-one-dimensional (1D) s = 1/2 frustrated spin-chain system linarite. Susceptibility, magnetization, specific heat, magnetocaloric effect, magnetostriction, and thermal-expansion measurements were performed to characterize the magnetic phase diagram. In particular, for magnetic fields along the b axis five different magnetic regions have been detected, some of them exhibiting short-range-order effects. The experimental magnetic entropy and magnetization are compared to a theoretical modeling of these quantities using density matrix renormalization group (DMRG) and transfer matrix renormalization group (TMRG) approaches. Within the framework of a purely 1D isotropic model Hamiltonian, only a qualitative agreement between theory and the experimental data can be achieved. Instead, it is demonstrated that a significant symmetric anisotropic exchange of about 10% is necessary to account for the basic experimental observations, including the three-dimensional (3D) saturation field, and which in turn might stabilize a triatic (three-magnon) multipolar phase. © 2013, American Physical Society.