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  1. Article ; Online: Reply to the 'Comment on "Investigation on the structure and thermoelectric properties of Cu

    Mukherjee, Shriparna / Chetty, Raju / Madduri, P V Prakash / Nayak, Ajaya K / Wojciechowski, Krzysztof / Ghosh, Tanmoy / Chattopadhyay, Kamanio / Suwas, Satyam / Mallik, Ramesh Chandra

    Dalton transactions (Cambridge, England : 2003)

    2020  Volume 49, Issue 17, Page(s) 5738–5740

    Language English
    Publishing date 2020-04-21
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472887-4
    ISSN 1477-9234 ; 1364-5447 ; 0300-9246 ; 1477-9226
    ISSN (online) 1477-9234 ; 1364-5447
    ISSN 0300-9246 ; 1477-9226
    DOI 10.1039/d0dt00412j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Investigation on the structure and thermoelectric properties of Cu

    Mukherjee, Shriparna / Chetty, Raju / Madduri, P V Prakash / Nayak, Ajaya K / Wojciechowski, Krzysztof / Ghosh, Tanmoy / Chattopadhyay, Kamanio / Suwas, Satyam / Mallik, Ramesh Chandra

    Dalton transactions (Cambridge, England : 2003)

    2019  Volume 48, Issue 3, Page(s) 1040–1050

    Abstract: Cu2Te is a superionic conductor that belongs to the Phonon Liquid Electron Crystal class of thermoelectric (TE) materials. Despite the simple chemical formula, the crystal structures and phases in the Cu2Te system have not been understood properly. In ... ...

    Abstract Cu2Te is a superionic conductor that belongs to the Phonon Liquid Electron Crystal class of thermoelectric (TE) materials. Despite the simple chemical formula, the crystal structures and phases in the Cu2Te system have not been understood properly. In this work, we study the structural and TE properties of Cu2Te (CT2), Cu1.6Te (CT1.6) and Cu1.25Te (CT1.25). The samples were synthesized via a solid-state reaction method. Powder X-ray diffraction analysis revealed that the samples have different crystal structures depending upon the Cu : Te stoichiometry. The elemental compositional analysis showed that all the samples are copper deficient. This is due to the precipitation of metallic copper on the surface of the ingot arising from the thermal dissociation of Cu2Te. The transport properties were measured in the temperature range 300 K-600 K. The electrical conductivity (σ) decreases with an increase in temperature indicating a metal-like behaviour for all the samples. The positive Seebeck coefficients (S) for all the samples indicates that majority charge carriers are holes. The sample CT2 has a higher S (29.5 μV K-1 at 573 K) and a lower σ (2513 S cm-1 at 573 K) due to a lower carrier (hole) concentration compared to the other two samples. With the increase in Cu deficiency, the hole concentration increases, and this leads to higher electronic thermal conductivity in the samples CT1.6 and CT1.25. The maximum thermoelectric figure of merit of 0.03 at 524 K is achieved for the sample CT2 owing to its higher power factor (0.24 mW m-1 K-2) and lower thermal conductivity (3.8 W m-1 K-1). The present study bridges the gap between the theoretical predictions and experimental observations involving the various possible structures in this system. Furthermore, we have shown that the Cu vacancies are detrimental to the thermoelectric performance of Cu2Te.
    Language English
    Publishing date 2019-01-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472887-4
    ISSN 1477-9234 ; 1364-5447 ; 0300-9246 ; 1477-9226
    ISSN (online) 1477-9234 ; 1364-5447
    ISSN 0300-9246 ; 1477-9226
    DOI 10.1039/c8dt04351e
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Order via subito

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  3. Book ; Online: Robust topological Hall effect driven by tunable noncoplanar magnetic state in Mn-Pt-In inverse tetragonal Heusler alloys

    Giri, Bimalesh / Mallick, Arif Iqbal / Singh, Charanpreet / Madduri, P. V. Prakash / Damay, Françoise / Alam, Aftab / Nayak, Ajaya K.

    2020  

    Abstract: Manipulation of magnetic ground states by effective control of competing magnetic interactions has led to the finding of many exotic magnetic states. In this direction, the tetragonal Heusler compounds consisting of multiple magnetic sublattices and ... ...

    Abstract Manipulation of magnetic ground states by effective control of competing magnetic interactions has led to the finding of many exotic magnetic states. In this direction, the tetragonal Heusler compounds consisting of multiple magnetic sublattices and crystal symmetry favoring chiral Dzyaloshinskii-Moriya interaction (DMI) provide an ideal base to realize non-trivial magnetic structures. Here, we present the observation of a large robust topological Hall effect (THE) in the multi-sublattice Mn$_{2-x}$PtIn Heusler magnets. The topological Hall resistivity, which originates from the non-vanishing real space Berry curvature in the presence of non-zero scalar spin chirality, systematically decreases with decreasing the magnitude of the canting angle of the magnetic moments at different sublattices. With help of first principle calculations, magnetic and neutron diffraction measurements, we establish that the presence of a tunable non-coplanar magnetic structure arising from the competing Heisenberg exchanges and chiral DMI from the D$_{2d}$ symmetry structure is responsible for the observed THE. The robustness of the THE with respect to the degree of non-collinearity adds up a new degree of freedom for designing THE based spintronic devices.

    Comment: 6 pages, 6 figures
    Keywords Condensed Matter - Materials Science
    Subject code 539
    Publishing date 2020-08-31
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Formation and magnetic properties of spark plasma sintered Mn$_{3-\delta}$ ($\delta$ = 0, 1) alloys

    Perween, Sonam / Rathi, A. / Singh, R. P. / Bhattacharya, A. / Raghuvanshi, Parul Rani / Madduri, P. V. Prakash / Rout, P. K. / Sivaiah, B. / Dhar, Ajay / Pant, R. P. / Gahtori, B. / Basheed, G. A.

    2019  

    Abstract: We present the synthesis of D0$_{22}$ Mn$_{3 - \delta}$Ga ($\delta$ = 0, 1) Heusler alloys by Spark Plasma Sintering method. The single phase Mn$_3$Ga (T$_\mathrm{c}$ $\simeq$ 780 K) is synthesized, while Mn$_2$Ga (T$_\mathrm{c}$ $\simeq$ 710 K) is found ...

    Abstract We present the synthesis of D0$_{22}$ Mn$_{3 - \delta}$Ga ($\delta$ = 0, 1) Heusler alloys by Spark Plasma Sintering method. The single phase Mn$_3$Ga (T$_\mathrm{c}$ $\simeq$ 780 K) is synthesized, while Mn$_2$Ga (T$_\mathrm{c}$ $\simeq$ 710 K) is found to coexist with a near-stoichiometric room temperature paramagnetic Mn$_9$Ga$_5$~($\approx$ 15 \%) phase due to its lower formation energy, as confirmed from our density functional theory (DFT) calculations. The alloys show hard magnetic behavior with large room temperature spontaneous magnetization m$_s$(80 kOe) = 1.63 (0.83) $\mu_\mathrm{B}$/f.u. and coercivity H$_\mathrm{c}$ = 4.28 (3.35) kOe for Mn$_3$Ga (Mn$_2$Ga). The magnetic properties are further investigated till T$_\mathrm{c}$ and the H$_\mathrm{c}$ (T) analysis by Stoner-Wohlfarth model shows the nucleation mechanism for the magnetization reversal. The experimental results are well supported by DFT calculations, which reveal that the ground state of D0$_{22}$ Mn$_2$Ga is achieved by the removal of Mn-atoms from full Heusler Mn$_3$Ga structure in accordance with half Heusler alloy picture.
    Keywords Condensed Matter - Materials Science
    Subject code 669
    Publishing date 2019-11-12
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

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