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Magneto-Transport in Mo-Doped LaMnO3...

Heng, Lee Yong,

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Magneto-Transport in Mo-Doped LaMnO3and Yig /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Magneto-Transport in Mo-Doped LaMnO3and Yig // Lee Yong Heng.
Author:	Heng, Lee Yong,
Description:	1 electronic resource (215 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-06, Section: B.
Contained By:	Dissertations Abstracts International86-06B.
Subject:	Software. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31777575
ISBN:	9798346773474

Magneto-Transport in Mo-Doped LaMnO3and Yig /
Heng, Lee Yong,

Magneto-Transport in Mo-Doped LaMnO3and Yig /Lee Yong Heng. - 1 electronic resource (215 pages)

Source: Dissertations Abstracts International, Volume: 86-06, Section: B.

The current demand in searching for materials that can be used to enhance the development of electronic and magnetic components to increase the efficiency in transformers, integrated sensors or even storage devices have rekindled the studies in the manganites. The enriching and vast studies on the A-site substitution have brought forth detailed phase diagram to describe the magnetic and electronic properties of A-site doped manganites.The parent compound LaMnO3 was reported to undergo self-doping mechanism which can give rise to mixed valence of Mn ions, i.e.: Mn4+ in the matrix of Mn3+, and hence brought forth many unexpected magnetic and electronic behaviours. Substituting trivalent, tetravalent, and pentavalent ions at the Mn-site induced Mn4+ into the Mn3+ system. The simultaneous occurrence of ferromagnetism and metallicity is understood in the framework of Zener's double exchange (DE) interaction. However, there were mixed reports on the ferromagnetism and electrical behaviours of these compounds. On the other hand, the substitution of hexavalent ion, such as Mo, has brought forth a mixed valence of Mn2+ in the matrix of Mn3+instead. The main motivation of this thesis is to synthesize LaMn1-xMoxO3 (for 0 ≤ x ≤ 0.10) and investigate how the physical properties, in particular dc magnetization, resistivity (), thermopower (S), ac magnetoresistance (ac MR) and dynamic magnetization, change with increasing level of Mosubstitution. The conventional solid-state heating route (CH) and microwave irradiation (MW) were used to prepare these samples.Field-cooled magnetization at 1 kOe indicates that the substitution of Mo ions at the Mn-site has raised the curie temperature (TC) from 140 K (TN of CHprepared LaMnO3) to 240 K (x = 0.04) which can be explained by the enhancement of DE interaction due to the presence of mixed valence of Mn ions. The MW-prepared LaMnO3 shows a TC = 230 K, which was widely reported due to the presence of Mn4+ in the Mn3+ system. The Tc of all MWprepared LaMn1-xMoxO3 samples were higher than the CH-prepared samples. For all Mo-doped samples, the TC was observed to decrease for x ≥ 0.06. Msat for all samples were derived from the MH isotherms measured at FM regime up to 10 kOe. For x ≤ 0.06, all samples exhibited closer agreement to the theoretically calculated Msat using the spin-only contribution of Mn2+ and Mn3+ instead of Mn3+ and Mn4+ . But for x > 0.06, the Msatshowed a closer agreement to the latter instead.All Mo-doped LaMnO3 showed an insulating-to-metallic transition near TC but the peak thermopower TS was significantly far from TC, showing the existence of Griffiths phase between TC and TS. Griffiths phase shows clear indication of the existence of ferromagnetic clusters above the TC.

English

ISBN: 9798346773474Subjects--Topical Terms:

619355
Software.

Magneto-Transport in Mo-Doped LaMnO3and Yig /
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245 1 0 $a Magneto-Transport in Mo-Doped LaMnO3and Yig / $c Lee Yong Heng.
264 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
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500 $a Source: Dissertations Abstracts International, Volume: 86-06, Section: B.
500 $a Advisors: Mahendiran, Ramanathan.
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520 $a The current demand in searching for materials that can be used to enhance the development of electronic and magnetic components to increase the efficiency in transformers, integrated sensors or even storage devices have rekindled the studies in the manganites. The enriching and vast studies on the A-site substitution have brought forth detailed phase diagram to describe the magnetic and electronic properties of A-site doped manganites.The parent compound LaMnO3 was reported to undergo self-doping mechanism which can give rise to mixed valence of Mn ions, i.e.: Mn4+ in the matrix of Mn3+, and hence brought forth many unexpected magnetic and electronic behaviours. Substituting trivalent, tetravalent, and pentavalent ions at the Mn-site induced Mn4+ into the Mn3+ system. The simultaneous occurrence of ferromagnetism and metallicity is understood in the framework of Zener's double exchange (DE) interaction. However, there were mixed reports on the ferromagnetism and electrical behaviours of these compounds. On the other hand, the substitution of hexavalent ion, such as Mo, has brought forth a mixed valence of Mn2+ in the matrix of Mn3+instead. The main motivation of this thesis is to synthesize LaMn1-xMoxO3 (for 0 ≤ x ≤ 0.10) and investigate how the physical properties, in particular dc magnetization, resistivity (), thermopower (S), ac magnetoresistance (ac MR) and dynamic magnetization, change with increasing level of Mosubstitution. The conventional solid-state heating route (CH) and microwave irradiation (MW) were used to prepare these samples.Field-cooled magnetization at 1 kOe indicates that the substitution of Mo ions at the Mn-site has raised the curie temperature (TC) from 140 K (TN of CHprepared LaMnO3) to 240 K (x = 0.04) which can be explained by the enhancement of DE interaction due to the presence of mixed valence of Mn ions. The MW-prepared LaMnO3 shows a TC = 230 K, which was widely reported due to the presence of Mn4+ in the Mn3+ system. The Tc of all MWprepared LaMn1-xMoxO3 samples were higher than the CH-prepared samples. For all Mo-doped samples, the TC was observed to decrease for x ≥ 0.06. Msat for all samples were derived from the MH isotherms measured at FM regime up to 10 kOe. For x ≤ 0.06, all samples exhibited closer agreement to the theoretically calculated Msat using the spin-only contribution of Mn2+ and Mn3+ instead of Mn3+ and Mn4+ . But for x > 0.06, the Msatshowed a closer agreement to the latter instead.All Mo-doped LaMnO3 showed an insulating-to-metallic transition near TC but the peak thermopower TS was significantly far from TC, showing the existence of Griffiths phase between TC and TS. Griffiths phase shows clear indication of the existence of ferromagnetic clusters above the TC.
546 $a English
590 $a School code: 1883
650 4 $a Software. $2 gtt. $3 619355
650 4 $a Spectrum analysis. $3 520440
650 4 $a Physical properties. $3 3564184
650 4 $a Energy consumption. $3 631630
650 4 $a Thin films. $3 626403
650 4 $a Permeability. $3 915594
650 4 $a Magnetic fields. $3 660770
650 4 $a Electric fields. $3 880423
650 4 $a Symmetry. $3 536815
650 4 $a Scanning electron microscopy. $3 551366
650 4 $a Analytical chemistry. $3 3168300
650 4 $a Condensed matter physics. $3 3173567
650 4 $a Electromagnetics. $3 3173223
650 4 $a Energy. $3 876794
650 4 $a Materials science. $3 543314
650 4 $a Optics. $3 517925
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710 2 $a National University of Singapore (Singapore). $e degree granting institution. $3 3765631
720 1 $a Mahendiran, Ramanathan $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 86-06B.
790 $a 1883
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792 $a 2023
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