A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

SrMn2P2 and CaMn2P2 are insulators that adopt the trigonal CaAl2Si2-type structure containing corrugated Mn honeycomb layers. Magnetic susceptibility χ and heat capacity versus temperature T data reveal a weak first-order antiferromagnetic (AFM) transition at the Néel temperature TN=53(1) K for SrMn2P2 and a strong first-order AFM transition at TN=69.8(3) K for CaMn2P2. Both compounds exhibit isotropic and nearly T-independent χ(T≤TN), suggesting magnetic structures in which nearest-neighbor moments are aligned at ≈120° to each other. The 31P NMR measurements confirm the strong first-order transition in CaMn2P2 but show critical slowing down above TN for SrMn2P2, thus also evidencing second-order character. The 31P NMR measurements indicate that the AFM structure of CaMn2P2 is commensurate with the lattice whereas that of SrMn2P2 is incommensurate. These first-order AFM transitions are unique among the class of (Ca, Sr, Ba)Mn2 (P, As, Sb, Bi)2 compounds that otherwise exhibit second-order AFM transitions. This result challenges our understanding of the circumstances under which first-order AFM transitions occur.

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Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽

10.3390/cryst11040378 ◽

2021 ◽

Vol 11 (4) ◽

pp. 378

Author(s):

Li Zhao ◽

Zhiwei Hu ◽

Hanjie Guo ◽

Christoph Geibel ◽

Hong-Ji Lin ◽

...

Keyword(s):

High Pressure ◽

Magnetic Properties ◽

Magnetic Susceptibility ◽

Crystal Growth ◽

Physical Properties ◽

Single Crystal ◽

Single Crystals ◽

Magnetic Moments ◽

Single Crystal Growth ◽

The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

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Suppression of Ferromagnetism in EuxCa1-xB6

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.190.97 ◽

2012 ◽

Vol 190 ◽

pp. 97-100 ◽

Cited By ~ 1

Author(s):

V.V. Glushkov ◽

A.V. Kuznetsov ◽

I. Sannikov ◽

A.V. Bogach ◽

S.V. Demishev ◽

...

Keyword(s):

Magnetic Properties ◽

Magnetic Susceptibility ◽

Curie Temperature ◽

Single Crystals ◽

Effective Magnetic Moment ◽

Paramagnetic State ◽

Low Field ◽

Wide Range ◽

Free Ion ◽

The Eu

We report the magnetic properties of EuxCa1-xB6 single crystals (0.756x1) studied in the wide range of temperatures (1.8-300 K) and magnetic fields (up to 50 kOe). It was found that low field magnetic susceptibility χ (T) follows the Curie-Weiss law χ~(T-Θp)-1 at high temperatures for all the concentrations studied. The effective magnetic moment of the Eu2+ ion estimated from the data diminishes from the free ion value μeff7.93μB (μB - Bohr magneton) for x=1 to μeff7.3μB for x=0.756. A universal behavior of magnetic susceptibility χ~(T-Θ)-α (α=1.5) is detected close to the Curie temperature TC in the paramagnetic state at both metallic (x>xC~0.8) and dielectric (xC.

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First-order valence transition and barocaloric effect in EuNi2(Si1−xGex)2

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2003.12.701 ◽

2004 ◽

Vol 272-276 ◽

pp. 2352-2354 ◽

Cited By ~ 8

Author(s):

Z. Hossain ◽

Th. Strässle ◽

C. Geibel ◽

A. Furrer

Keyword(s):

Valence Transition ◽

First Order

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Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

Journal of Materials Research ◽

10.1557/jmr.2002.0429 ◽

2002 ◽

Vol 17 (11) ◽

pp. 2960-2965 ◽

Cited By ~ 4

Author(s):

E. Arushanov ◽

L. Ivanenko ◽

D. Eckert ◽

G. Behr ◽

U. K. Rößler ◽

...

Keyword(s):

Activation Energy ◽

Magnetic Properties ◽

Magnetic Susceptibility ◽

External Field ◽

Single Crystals ◽

Spin Glasses ◽

Paramagnetic Centers ◽

Temperature Dependent ◽

Paramagnetic Curie Temperature ◽

Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

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Twinned olivenite from Cap Garonne, Mine du Pradet – structure and magnetic behavior

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2019-0063 ◽

2020 ◽

Vol 235 (1-2) ◽

pp. 7-13

Author(s):

Jutta Kösters ◽

Christian Paulsen ◽

Frank Stegemann ◽

Birgit Heying ◽

Valérie Galéa-Clolus ◽

...

Keyword(s):

Magnetic Susceptibility ◽

Single Crystals ◽

Cluster Model ◽

Spin Exchange ◽

Magnetic Behavior ◽

Exchange Parameter ◽

X Ray Diffraction ◽

X Ray ◽

Spin Cluster ◽

Antiferromagnetic Spin

AbstractSystematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/kB = 157(3) K.

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