Home  Group of the Electronic Properties of the Narrow-band Conductors

 

Research direction: Static and Dynamic Magnetic Properties of the Compounds Based
on the d – f – Elements: Relation to Electronic and Crystal Structures.

 

Up to 2011 the group was headed by Anatoly B. Beznosov, PhD (Phys&Math), Senior Researcher

Since 2011, the group led by  Elena L. Fertman, DSc (Phys&Math), Senior Researcher

 

Personnel:

Elena L. Fertman, DSc. (Phys&Math), Senior Researcher

Oksana V. Kravchyna, PhD (Phys&Math), Junior Researcher

 

Main recent  results

1. A structural 1-st-order cooperative phase transition (of martensitic type) R3C – Imma has been first revealed in a colossal magnetoresistance (CMR) La2/3Ba2/3MnO3 perovskite in the vicinity of ТS ~ 200 K. The transformation found leads to the phase segregated state of the compound, when two different structures are coexistent, both being ferromagnetic, below the room temperature. Pronounced hysteretic anomalies of magnetic and ultrasound properties, as well as nonequilibrium thermodynamics, have been found in the phase transformation region.

·      A. Beznosov, V. Desnenko, E. Fertman, C. Ritter, D. Khalyavin, Magnetic and neutron diffraction study of La2/3Ba1/3MnO3 perovskite manganite // Phys. Rev. B 68, #5, 054109 1- 054109 11 (2003).

·      Fertman E., Ritter C., Beznosov A., Desnenko V., Khalyavin D. Crystallographic Phases in La2/3Ba1/3MnO3: Temperature Transformations and Relation to Magnetism // Physica B: Condens. Matter. -2004. -V. 350, #1-3. –P. 227-230.

·      Fertman E.L., Beznosov A.B., Desnenko V.A., Pal-Val L.N., Pal-Val P.P., Khalyavin D.D. Singularities of magnetic and elastic characteristics of La2/3Ba1/3MnO3: Analysis of martensitic kinetics // J. Magn. Magn. Mater. - 2007. - V.308, # 2. - Р. 278-283.

·      Beznosov A. B., Fertman E. L., Desnenko V. A., Feher A., Kajnakova M., Ritter C.,
Khalyavin D. Low-temperature phase segregation in La2/3Ba1/3MnO3: Manifestation of nonequilibrium thermodynamics // ФНТ. – 2009. - Т.35, №6. – С. 571-577; -Low Temp. Phys. – 2009. - V. 35, #6, p. 449-454 (2009)

 

2. For the first time it was revealed that CMR compound Nd2/3Ca1/3MnO3 exhibits a sequence of magnetic transformations at low temperatures: two antiferromagnetic ones at TN1 ~ 130 K and TN2 ~ 80 K, and a ferromagnetic one at T~ 70 K. It leads to the self organized phase segregated state of the compound below the room temperature, when at least three different magnetic phases are coexistant: the two antiferromagnetic charge ordered ones (AFM) (their fraction is about 82%) and the ferromagnetic charge disordered (FM) one (its phase fraction is about 18%).

·      Fertman E., Sheptyakov D., Beznosov A., Desnenko V., Khalyavin D. Exchange Interactions and Magnetic Subsystem in Nd2/3Ca1/3MnO3: Analysis of Temperature Effects // Physica B: Condens. Matter. -2004. -V. 350, #1-3S. –P. E9-E12.

·      Fertman E., Sheptyakov D., Beznosov A., Desnenko V., Khalyavin D.  Magnetic states and the crystal volume of Nd2/3Ca1/3MnO3: analysis of phase transformations // J. Magn. Magn. Mater. - 2005. - V.293, #2. - Р. 787-792.

 

3. It was first revealed that the low temperature magnetic nanoscale phase-segregated state of Nd2/3Ca1/3MnO3 originates from the charge ordering that takes place at much higher temperature TCO » 212 K and possesses a martensitic nature, leading to the self-organized coexistence of charge ordered and charge disordered phases in the wide temperature range below the room temperature.

For the first time experimentally was shown a sharp decrease of the Mn-O2 bond lengths below TCO for Nd2/3Ca1/3MnO3 perovskite associated with a bond-centered charge density wave.

·      Безносов А.Б., Фертман Е.Л., Десненко В.А.. Зарядовое упорядочение, внутренние структурные параметры и магнитная восприимчивость Nd2/3Ca1/3MnO3: движущие силы фазового перехода // ФНТ. – 2008. - Т.34, №8. - С. 790-797.

 

4. Magnetic phase transformations temperatures as well as those of charge ordering have been found to be structural-dependent (Nd1-хYx)2/3Ca1/3MnO3 (x = 0; 0.1) compounds. Y doping leads to the decrease of the anisotropy of the orthorhombic Pnma crystal lattice , which causes a decrease of the indirect exchange parameters in the system and thus a decrease of the magnetic transformation temperatures for 20-30 K in the doped compound. Doping leads as well to the higher level of the coherent Jahn-Teller distortions of the MnO6 octahedra in the 200-300 K temperature region, which results in the increase of the charge ordering temperature for ~ 80 K.

·      Fertman E., Beznosov A., Desnenko V., Kajnakova M., Feher A.  Phase transformations in Nd2/3Ca1/3MnO3: Effect of Y substitution // Solid State Phenomena. - 2009. – V. 152-153, P. 108-111.

·      Fertman E., Beznosov A., Sheptyakov D., Desnenko V., Kajnakova M., Feher A., Khalyavin D. Effect of Y-doping on the Magnetic and Charge Orderings in Nd2/3Ca1/3MnO3 // J. Magn. Magn. Mater. – 2009. - V.321, # 4. - Р. 316-320.

 

5. Clear experimental evidence of the cluster-glass magnetic behavior of Nd2/3Ca1/3MnO3  compound below freezing temperature Tg » 60 K has been revealed. Slow relaxation process and a variety of relaxation times found at low temperatures confirm a cluster glass state, which may be ascribed to the competing interaction between the coexisting FM and AFM phases. It was found that the relaxation mechanisms below the cluster glass freezing temperature Tg ~ 60 K and above this temperature are strongly different.

·      A. Feher, M. Kajňaková, Е. Л. Фертман, А. Б. Безносов, В. А. Десненко, С. Н. Доля, Наномасштабное фазовое расслоение и кластерное стекло в Nd2/3Ca1/3MnO3 // Наносистеми, наноматеріали, нанотехнології, т. 9, №1, с.с. 189 – 196, 2011.

·      M. Kajňaková, A. Feher, E. Fertman, V. Desnenko, A. Beznosov, S. Dolya, Nanophase Separation and Magnetic Spin Glass in Nd2/3Ca1/3MnO3 // Solid State Phenomena (to be published in 2012).

 

6. A giant exchange bias in CMR Nd2/3Ca1/3MnO3 perovskite at low temperatures has been first revealed, evident of an intrinsic exchange coupling in this compound and its nano-phase segregated state, namely the presence of small ferromagnetic clusters immersed in the charge-ordered antiferromagnetic phase

·      Alexander Feher, Vladimir Desnenko, Elena Fertman, Sergiy Dolya, Marcela Kajňaková and Anatoly Beznosov, Direct evidence of the low temperature cluster-glass magnetic state of Nd2/3Ca1/3MnO3 perovskite // ФНТ. – 2012. - Т.  , №  . - С.   (to be published).

 

7. A strong exchange coupling between Nd and Mn magnetic subsystems has been found in (Nd1-хYx)2/3Ca1/3MnO3 (x = 0; 0.1) compounds. A broadened Schottky-like anomaly below 20 K has been found, which is caused by the splitting of the Nd3+ ions ground-state doublet in the effective molecular field Hex of Mn spin system. The Nd-ions magnetic ordering has been found below 30 K.  

The broadening of the Schottky anomaly is attributed to the non-equivalent sites of Nd³+ ions, which is probably induced by a phase segregated state of the compound. Applied magnetic field moves the Schottky peak to higher temperatures, playing a role of an additional magnetic field on the Nd ion sites.

The Nd-ions magnetic ordering has been found below 30 K.

·      Fertman E, Beznosov A, Desnenko V, Kajnakova M, Feher A. Low temperature heat capacity of Nd2/3Ca1/3MnO3 and (Nd0.9Y0.1)2/3Ca1/3MnO3 manganites: transformation of the Schottky-like anomaly // J. Phys.: Conf. Ser. – 2009. - V. 150, #4. - P. 042031 1-4.

·      Fertman E., Beznosov A., Sheptyakov D., Desnenko V., Kajnakova M., Feher A., Khalyavin D. Effect of Y-doping on the Magnetic and Charge Orderings in Nd2/3Ca1/3MnO3 // J. Magn. Magn. Mater. – 2009. - V.321, # 4. - Р. 316-320.

·      A Beznosov, E Fertman, V Desnenko, A Feher, M Kajnakova, and A Loginov,  Crystal-field and Nd-Mn exchange interaction in Nd2/3Ca1/3MnO3 // J. Phys.: Conf. Ser., 200, 032007 (1-4) (2010).

·      Anatoly Beznosov,  Elena Fertman, Vladimir Desnenko, Marcela Kajňaková and Alexander Feher, The Nd-Mn exchange interaction, low temperature specific heat and magnetism of Nd2/3Ca1/3MnO3  // J. Magn. Magn. Mater. 323, Iss.18-19 p. 2380-2385 (2011).

 

8. The low temperature specific heat of the CMR compounds (NdxY1-x)2/3Ca1/3MnO3 (x=0, 0.1) for 0.4 £ T < 2 K in magnetic fields up to H = 9 T has been studied. Applied magnetic fields lead to the drop of the low temperature specific heat by more than 2 orders, which implies a large magnetic contribution.

·      Feher, S. Dolya, E. Fertman, M. Kajňaková, V. Desnenko, J. Šebek, and E. Šantavá, Analysis of the low temperature magnetic contributions to the specific heat of (NdxY1-x)2/3Ca1/3MnO3 (x=0, 0.1) // Journal of Low Temperature Physics (USA) 2011, V. 162, Iss. 5, p. 529-535).

 

 

Selected earlier results and publications:

1. The conception of new quasi-particles ("j-polarons") was introduced in the physics of heavy rare earth metals. The temperature dependence was explained of the optical absorption of the Gd single crystal at the frequency of the d- f- exchange resonance.

·      1. The conception of new quasi-particles ("j-polarons") was introduced in the physics of heavy rare earth metals. The temperature dependence was explained of the optical absorption of the Gd single crystal at the frequency of the d- f- exchange resonance.

·      A. B. Beznosov, V. P. Gnezdilov, and V. V. Eremenko, d-f-Exchange resonance and "j-polaron" in the metallic gadolinium, Pis'ma v ZhETF, 38, 486-488 (1983); JETP Letters, 38, (1983).

·      A. B. Beznosov, V. V. Eremenko, and V. P. Gnezdilov, d-f-Exchange resonance in gadolinium: theory and experiment, J. Magn. Magn. Mater., 43, 243-248 (1984).

·      A. B. Beznosov, V. P. Gnezdilov, and V. V. Eremenko, Coherent interaction of light with atomic dipole moments in single-crystalline gadolinium, Fiz. Nizk. Temp., 10, 954-968 (1984); Sov. J. Low Temp. Phys., 10, 498-505 (1984).

2. Three new magnetic phase transitions were discovered and studied in the Gd-Y alloys. Their classification and identification of the magnetic structures were carried out. The mechanism of the formation of magnetic state of the system was suggested.

·      A. B. Beznosov, P. P. Pal-Val, E. L. Fertman, Low Temperature Elasticity and Magnetic Susceptibility of Gd-Y Alloys, Advances in Cryogenic Engineering, 43, 1557-1564 (1998);

·      A. B. Beznosov, E. L. Fertman, P. P. Pal-Val, Curious magnetic phase transition in polycrystalline Gd-Y alloys: ultraacoustic study, J. Magn. Magn. Mater. 192, 111-115 (1999);

·      A. B. Beznosov, E. L. Fertman, V. V. Eremenko, P. P. Pal-Val, V. P. Popov, N. N. Chebotayev, Spontaneous magnetostriction in the Gd-Y system: analysis of phase transformations, Fiz. Nizk. Temp., 27, 430-435 (2001); Low Temp. Phys., 27, 320-324 (2001).

3. The anomalies of the electronic structure and magnetoelastic properties of the Fe-B metglasses in the vicinity of the eutectic composition were discovered. The observed effects were interpreted on the base of the concept of the special stability of the electronic structure of clusters of the eutectic composition, corresponding to the quasicrystal atomic coordination.

·      Beznosov A.B., Fertman E.L., Eremenko V.V., Desnenko V.A., Bengus V.Z., Low Temperature Magnetic Properties and Stress Effects in Glassy Fe-B Alloys: the Eutectic Region, Fiz. Nizk. Temp., 25, 857-860 (1999); Low Temp. Phys. 25, 641-644 (1999).

·      A. B. Beznosov, E. L. Fertman, V. V. Eremenko, V. A. Desnenko, Electronic structure and magnetostrictive sensitivity of Fe-B metallic glasses, Fiz. Nizk. Temp., 27, 425-429 (2001); Low Temp. Phys. 27, 316-319 (2001).

4. A model of conductivity of the narrow band magnetic conductor describing the «colossal magnetoresistance effect» in manganese oxides was proposed. The model parameters dependent on the magnetization are the gap in the electron energy spectrum, the effective mass and transport relaxation time of the charge carriers.

·      Beznosov A.B., Belevtsev B.I., Fertman E.L., Desnenko V.A., Naugle D.G., Rathnayaka K.D.D., Parasiris A. , Exchange interaction and magnetoresistance in La2/3Ca1/3MnO3: experiment and models, Fiz. Nizk. Temp. 28, 774-780 (2002); Low Temp. Phys., 28, 556-561 (2002).

5. Three magnetic phase transitions below the Curie point and the electronic phase transition coinciding with the structural phase transition of martensitic type have been revealed and studied in the La2/3Ba1/3MnO3 perovskite manganite.

·      A. Beznosov, V. Desnenko, E. Fertman, C. Ritter, D. Khalyavin, Magnetic and neutron diffraction study of La2/3Ba1/3MnO3 perovskite manganite, Phys. Rev. B 68, 054109 1- 054109 11 (2003).

6. Magnon characteristics, amplitudes of the spin-phonon interaction, magneto-dipole oscillator forces, and the ferromagnetic ordering temperature are calculated for the half metal system.

·      A. B. Beznosov and E. S. Orel, Spectrum of dynamic magnetic susceptibility of a randomized f-d magnet with spin-lattice coupling. I. Shift of the magnetic resonance frequencies. Low Temp. Phys., 30, 721-728; II. “Opening” of the spin excitation bands. Low Temp. Phys., 30, 790-798 (2004)

 

Some earlier publications:

1. A. B. Beznosov, E. S. Orel, Dinamic dielectric susceptibility tensor of a randomized f-d magnet, Fiz. Nizk. Temp., 27, 508-518 (2001); Low Temp. Phys., 27, 372-379 (2001).

2. A. B. Beznosov, P. P. Pal-Val, B. I. Belevtsev, V. B. Krasovitsky, E. L. Fertman, L. N. Pal-Val, I. N. Chukanova, T. G. Deineka, Electronic structure, magnetic order and conductivity of La 0.5Sra 0.5CoO3, Izvestia AN, Ser. Fiz., 66, 758-760 (2002) (in Russian).

3. A. B. Beznosov, E. L. Fertman, P. P. Pal-Val, V. A. Desnenko, V. B. Krasovitsky, A. B. Rinkevich, A. P. Nossov, V. G. Vassiliev, Elastic, magnetic and electric properties of Nd0.6Y0.06Ca0.3MnO3: effects of ordering and randomization, Izvestia AN, Ser. Fiz., 66, 758-760 (2002) (in Russian).

 

International scientific cooperation:

The group carries out joint researches with a number of foreign scientific centers. The works which were resulted in joint publications were performed in a cooperation with researches of the following institutes: IEP SAS, Kosice (Slovakia), IP CAS, Prague (Czech Republic), IMP PAS, Poznan (Poland), IP AMU, Poznan (Poland), ILTPSR PAS, Wrozlaw (Poland), IMP UD RAS, Ekaterinburg (Russia), IPSS BAS, Minsk (Belarus), ILL CNRS, Grenoble (France), PSI, Villigen (Switzerland), University of Antwerpen, (Belgium).

 

 

 

Selected Publications

1.      A. B. Beznosov, V. V. Eremenko, E. L. Fertman, V. A. Desnenko, D. D. Khalyavin, Magnetic phases in La0.66Ba0.34MnO3: effects of temperature and elastic strains // Fiz. Nizk. Temp. 28, 1065 (2002); Low Temp. Physics, 28, 762 (2002).

2.      А.Б.Безносов, П.П.Паль-Валь, Б.И.Белевцев, В.Б.Красовицкий, Е.Л.Фертман, Л.Н.Паль-Валь, И.Н.Чуканова, Т.Г.Дейнека. Электронная структура, магнитный порядок и проводимость La 0.5Sr 0.5CoO3. // Изв. АН, Сер. Физ., 2002, т. 66, №6, с. 758-760.

3.      А.Б.Безносов, Е.Л.Фертман, П.П.Паль-Валь, В.А.Десненко, В.Б.Красовицкий, А.Б.Ринкевич, А.П.Носов, В.Г.Васильев. Упругие, магнитные и электрические свойства Nd0.6Y0.06Ca0.3MnO3 : эффекты упорядочения и хаотизации // Изв. АН, Сер. Физ., 2002, т. 66, №6, с. 761-763.

4.      A. B. Beznosov, B. I. Belevtsev, E. L. Fertman, V. A. Desnenko, D. G. Naugle, K. D. D. Rathnayaka, A. Parasiris, Exchange interaction and magnetoresistance in La2/3Ca1/3MnO3: experiment and models // Fiz. Nizk.Temp. 28, 774 (2002); Low Temp. Physics, 28, 556 (2002).

5.      A. Beznosov, E. Fertman, V. Desnenko, D. Khalyavin, Uniaxial  pressure effect on magnetic susceptibility of perovskite manganite La0.66Ba0.34MnO3 // JMMM, 241, #1, 69-72 (2002).

6.      A. Beznosov, V. Desnenko, E. Fertman, C. Ritter, D. Khalyavin, Magnetic and neutron diffraction study of La2/3Ba1/3MnO3 perovskite manganite // Phys. Rev. B 68, #5, 054109 1- 054109 11 (2003).

7.      Белевцев Б. И., Кириченко А. Я., Черпак Н. Т., Голубничая Г. В., Максимчук И. Г.,
Безносов А. Б., Красовицкий В. Б., Паль-Валь П. П., Чуканова И. Н.
Эффект гигантского радиочастотного магнитопоглощения в кобальтите La0.5Sr0.5CoO3 // Известия Академии Наук, Серия Физическая. –2004. -Т.68, №5. -С. 674-677.

8.      Fertman E., Ritter C., Beznosov A., Desnenko V., Khalyavin D. Crystallographic Phases in La2/3Ba1/3MnO3: Temperature Transformations and Relation to Magnetism // Physica B: Condens. Matter. -2004. -V. 350, #1-3. –P. 227-230.

9.      Fertman E., Sheptyakov D., Beznosov A., Desnenko V., Khalyavin D. Exchange Interactions and Magnetic Subsystem in Nd2/3Ca1/3MnO3: Analysis of Temperature Effects // Physica B: Condens. Matter. -2004. -V. 350, #1-3S. –P. E9-E12.

10.  Fertman E., Sheptyakov D., Beznosov A., Desnenko V., Khalyavin D.  Magnetic states and the crystal volume of Nd2/3Ca1/3MnO3: analysis of phase transformations // J. Magn. Magn. Mater. - 2005. - V.293, #2. - Р. 787-792.

11.  Fertman E.L., Beznosov A.B., Desnenko V.A., Pal-Val L.N., Pal-Val P.P., Khalyavin D.D. Singularities of magnetic and elastic characteristics of La2/3Ba1/3MnO3: Analysis of martensitic kinetics // J. Magn. Magn. Mater. - 2007. - V.308, # 2. - Р. 278-283.

12.  Безносов А.Б., Фертман Е.Л., Десненко В.А.. Зарядовое упорядочение, внутренние структурные параметры и магнитная восприимчивость Nd2/3Ca1/3MnO3: движущие силы фазового перехода // ФНТ. – 2008. - Т.34, №8. - С. 790-797.

13.  Fertman E, Beznosov A, Desnenko V, Kajnakova M, Feher A. Low temperature heat capacity of Nd2/3Ca1/3MnO3 and (Nd0.9Y0.1)2/3Ca1/3MnO3 manganites: transformation of the Schottky-like anomaly // J. Phys.: Conf. Ser. – 2009. - V. 150, #4. - P. 042031 1-4.

14.  Fertman E., Beznosov A., Desnenko V., Kajnakova M., Feher A.  Phase transformations in Nd2/3Ca1/3MnO3: Effect of Y substitution // Solid State Phenomena. - 2009. – V. 152-153, P. 108-111.

15.  Fertman E., Beznosov A., Sheptyakov D., Desnenko V., Kajnakova M., Feher A., Khalyavin D. Effect of Y-doping on the Magnetic and Charge Orderings in Nd2/3Ca1/3MnO3 // J. Magn. Magn. Mater. – 2009. - V.321, # 4. - Р. 316-320.

16.  Beznosov A. B., Fertman E. L., Desnenko V. A., Feher A., Kajnakova M., Ritter C.,
Khalyavin D. Low-temperature phase segregation in La2/3Ba1/3MnO3: Manifestation of nonequilibrium thermodynamics // ФНТ. – 2009. - Т.35, №6. – С. 571-577; -Low Temp. Phys. – 2009. - V. 35, #6, p. 449-454 (2009).

17.  A Beznosov, E Fertman, V Desnenko, A Feher, M Kajnakova, and A Loginov,  Crystal-field and Nd-Mn exchange interaction in Nd2/3Ca1/3MnO3 // J. Phys.: Conf. Ser., 200, 032007 (1-4) (2010).

18.  Е. Фертман, А. Безносов, Естественные среды с отрицательным показателем преломления: перспективы сложных окислов переходных металлов // ФНТ 37, № 7, 2011, 721-735.

19.  Feher, S. Dolya, E. Fertman, M. Kajňaková, V. Desnenko, J. Šebek, and E. Šantavá, Analysis of the low temperature magnetic contributions to the specific heat of (NdxY1-x)2/3Ca1/3MnO3 (x=0, 0.1) // Journal of Low Temperature Physics (USA) 2011, V. 162, Iss. 5, p. 529-535).

20.  Anatoly Beznosov,  Elena Fertman, Vladimir Desnenko, Marcela Kajňaková and Alexander Feher, The Nd-Mn exchange interaction, low temperature specific heat and magnetism of Nd2/3Ca1/3MnO3  // J. Magn. Magn. Mater. 323, Iss.18-19 p. 2380-2385 (2011).

21.  A. Feher, M. Kajňaková, Е. Л. Фертман, А. Б. Безносов, В. А. Десненко, С. Н. Доля, Наномасштабное фазовое расслоение и кластерное стекло в Nd2/3Ca1/3MnO3 // Наносистеми, наноматеріали, нанотехнології, т. 9, №1, с.с. 189 – 196, 2011.

22.  M. Kajňaková, A. Feher, E. Fertman, V. Desnenko, A. Beznosov, S. Dolya, Nanophase Separation and Magnetic Spin Glass in Nd2/3Ca1/3MnO3 // Solid State Phenomena (to be published in 2012).

23.  Alexander Feher, Vladimir Desnenko, Elena Fertman, Sergiy Dolya, Marcela Kajňaková and Anatoly Beznosov, Direct evidence of the low temperature cluster-glass magnetic state of Nd2/3Ca1/3MnO3 perovskite // ФНТ. – 2012. - Т.  , №  . - С.   (to be published).

 

 

 

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