Paramagnetic—spin-glass—antiferromagnetic phase transitions inCd1−xMnxTefrom specific heat and magnetic susceptibility measurements

1980 ◽  
Vol 22 (7) ◽  
pp. 3344-3355 ◽  
Author(s):  
R. R. Galazka ◽  
Shoichi Nagata ◽  
P. H. Keesom
Keyword(s):  
Magnetic Susceptibility ◽  
Phase Transitions ◽  
Specific Heat ◽  
Spin Glass ◽  
Antiferromagnetic Phase

scholarly journals Effects of Non-Stoichiometry on the Ground State of the Frustrated System Li0.8Ni0.6Sb0.4O2

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6785
Author(s):  
Evgeniya Vavilova ◽  
Timur Salikhov ◽  
Margarita Iakovleva ◽  
Tatyana Vasilchikova ◽  
Elena Zvereva ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Specific Heat ◽  
Spin Glass ◽  
Short Range ◽  
Freezing Temperature ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
7Li Nmr

The non-stoichiometric system Li0.8Ni0.6Sb0.4O2 is a Li-deficient derivative of the zigzag honeycomb antiferromagnet Li3Ni2SbO6. Structural and magnetic properties of Li0.8Ni0.6Sb0.4O2 were studied by means of X-ray diffraction, magnetic susceptibility, specific heat, and nuclear magnetic resonance measurements. Powder X-ray diffraction data shows the formation of a new phase, which is Sb-enriched and Li-deficient with respect to the structurally honeycomb-ordered Li3Ni2SbO6. This structural modification manifests in a drastic change of the magnetic properties in comparison to the stoichiometric partner. Bulk static (dc) magnetic susceptibility measurements show an overall antiferromagnetic interaction (Θ = −4 K) between Ni2+ spins (S = 1), while dynamic (ac) susceptibility reveals a transition into a spin glass state at a freezing temperature TSG ~ 8 K. These results were supported by the absence of the λ-anomaly in the specific heat Cp(T) down to 2 K. Moreover, combination of the bulk static susceptibility, heat capacity and 7Li NMR studies indicates a complicated temperature transformation of the magnetic system. We observe a development of a cluster spin glass, where the Ising-like Ni2+ magnetic moments demonstrate a 2D correlated slow short-range dynamics already at 12 K, whereas the formation of 3D short range static ordered clusters occurs far below the spin-glass freezing temperature at T ~ 4 K as it can be seen from the 7Li NMR spectrum.

Magnetic susceptibility, specific heat, and the spin-glass transition inHg1−xMnxTe

1980 ◽  
Vol 22 (7) ◽  
pp. 3331-3343 ◽  
Author(s):  
Shoichi Nagata ◽  
R. R. Galazka ◽  
D. P. Mullin ◽  
H. Akbarzadeh ◽  
G. D. Khattak ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Glass Transition ◽  
Specific Heat ◽  
Spin Glass ◽  
Spin Glass Transition

Specific heat, magnetic susceptibility, and the spin-glass transition inHg1−xMnxSe

1981 ◽  
Vol 23 (7) ◽  
pp. 3553-3554 ◽  
Author(s):  
Gul Dad Khattak ◽  
C. D. Amarasekara ◽  
S. Nagata ◽  
R. R. Galazka ◽  
P. H. Keesom
Keyword(s):  
Magnetic Susceptibility ◽  
Glass Transition ◽  
Specific Heat ◽  
Spin Glass ◽  
Spin Glass Transition

HIGH RESOLUTION CALORIMETRIC STUDIES AT PHASE TRANSITIONS OF ALKYLCYANOBIPHENYL LIQUID CRYSTALS CONFINED TO SUBMICRON SIZE CYLINDRICAL CAVITIES

1995 ◽  
Vol 09 (18n19) ◽  
pp. 2247-2283 ◽  
Author(s):  
DANIELE FINOTELLO ◽  
GERMANO S. IANNACCHIONE
Keyword(s):  
Phase Transitions ◽  
Liquid Crystals ◽  
High Resolution ◽  
Specific Heat ◽  
Pore Wall ◽  
Isotropic Phase ◽  
First Order ◽  
Smectic A ◽  
Nematic Director ◽  
Scalar Order Parameter

We review results of a high resolution systematic study of the specific heat for alkyl-cyanobiphenyl liquid crystals confined to the 0.2µm diameter cylindrical pores Anopore membranes. The nematic director alignment at the pore wall is varied from homeotropic to tangential by pore surface treatment. Several phenomena are uncovered by these studies which probed the weakly first order nematic to isotropic, the continuous smectic-A to nematic and the first order smectic-A to isotropic phase transitions. The specific heat is strongly dependent on the nematic director configuration, and confinement effects are remarkably distinct according to the order of the phase transition. The influence of elastic distortions and surface ordering and disordering effects are evident. Despite considerable departures from bulk behavior with regards to specific heat peaks size, rounding and width, and transition temperature shifts, a bulk-like critical behavior appears to be retained. The formation of smectic translational order within the pores is hindered for those liquid crystals that also possess a nematic phase. The average scalar order parameter temperature dependence is extracted from the specific heat results using a simplified Landau-de Gennes type of model, and is shown to be consistent with nuclear magnetic resonance results.

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