Multiphase segregation and metal-insulator transition in single crystal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">La</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn><mml:mo>/</mml:mo><mml:mn>8</mml:mn><mml:mi>−</mml:mi><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Pr</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow>

Kiryukhin, V.; Kim, B. G.; Podzorov, Vitaly; Cheong, Sang‐Wook; Koo, Tae‐Yeong; Hill, J. P.; Moon, Il; Jeong, Yoon Hee

doi:10.1103/physrevb.63.024420

Cited by 73 publications

(52 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is also apparent in thin films studied here from the hysteretic behavior of resistivity. The charge-order exists in LPCMO both below and above T MI [25] with a change in the CO fraction with temperature and magnetic field [8]. The insulating behavior above T MI of the LPCMO films studied here can be attributed to the presence of the CO phase.…”

mentioning

confidence: 59%

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

et al. 2008

View full text Add to dashboard Cite

Variable temperature scanning tunneling microscopy/spectroscopy studies on (110) oriented epitaxial thin films of La0.350Pr0.275Ca0.375MnO3 are reported in the temperature range of 77 to 340 K. The films, grown on lattice matched NdGaO3 substrates, show a hysteretic metal-insulator transition in resistivity at 170 K. The topographic STM images show step-terrace morphology while the conductance images display a nearly homogeneous surface. The normalized conductance spectra at low temperatures (T<150 K) show an energy gap of 0.5 eV while for T≥180 K a gap of 0.16 eV is found from the activated behavior of the zero bias conductance. The presence of energy gap and the absence of phase separation on the surface over more than 2 µm×2 µm area contradicts the metallic behavior seen in resistivity measurements at low temperatures. We discuss the measured energy gap in terms of the stabilization of the insulating CO phase at the film surface. PACS numbers:The research over past decade on colossal magnetoresistive (CMR) manganites [1,2,3] has led to a number of very interesting phenomena. These are now understood to be systems with strongly coupled charge, spin, lattice, and orbital degrees of freedom with a number of possible phases of nearly equal free energies [2,4,5]. These phases are thought to coexist in some manganite compositions and the relative fractions of phase are sensitive to external perturbations such as magnetic field, electric field, pressure, and strain. In fact, a sudden termination of the periodic potential at the surface is a perturbation that seems to make the surface quite different from the bulk [6]. The bulk of some of the small band-width manganites [7] undergoes an electronic phase-separation [8,9] into metallic and insulating regions, which is thought [4, 5, 10] to be responsible for the CMR effect. Various research groups have observed multiple phases in some of the manganites, in particular, in (La 1−x Pr x ) 0.625 Ca 0.375 MnO 3 series, using different probes [8,11,12] including Scanning Tunneling Microscopy / Spectroscopy (STM/S) [13,14,15,16]. However, the detailed electronic nature of the individual phases is far from understood [2].In this work, we have probed the surface of a relatively narrow band-width hole-doped manganite La 0.350 Pr 0.275 Ca 0.375 MnO 3 (LPCMO), using the STM/S in the temperature range of 77K to 340K. The ground state of the two end members of this compound La 0.675 Ca 0.375 MnO 3 and Pr 0.675 Ca 0.375 MnO 3 are ferromagnetic metal and antiferromagnetic charge-ordered (CO) insulator, respectively. Intermediate compositions show a CO transition around 200 K with coexisting CO insulating and charge-disordered conducting phases [8]. Our main objective in this study has been to probe various phases in LPCMO films by local tunneling spectroscopy to understand their nature and contribution to CMR. However, we find that the low energy part of the spectra evolves quite homogeneously with temperature with an energy gap that changes from 0.16 eV to 0.5 eV on cooling. Whilst t...

show abstract

mentioning

confidence: 59%

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

et al. 2008

View full text Add to dashboard Cite

show abstract

“…[2] Intense research activities in these compounds were developed by Moscow groups [3][4][5] and by Cheongś group. [6][7][8][9][10][11][12] In short, these works show the tendency of LPCM(y) to form inhomogeneous structures, which seems to be a generic property of strongly correlated systems. [2,13] There are conclusive evidences, both theoretical [14,15]and experimental, [16,17] showing that the high values of MR achieved by PS manganites are due to the possibility of unbalancing the amount of the coexisting phases by the application of low magnetic fields.…”

mentioning

confidence: 76%

Nonvolatile magnetoresistive memory in phase separatedLa0.325Pr0.300Ca

et al. 2002

View full text Add to dashboard Cite

We have measured magnetic and transport response on the polycrystalline La 5/8−y PryCa 3/8 MnO3 (y = 0.30, average grain size 2 microns ) compound. In the temperature range where ferromagnetic metallic and insulating regions coexist we observed a persistent memory of low magnetic fields ( < 1 T) which is determined by the actual amount of the ferromagnetic phase. The possibility to manipulate this fraction with relatively small external perturbations is related to the phase separated nature of these manganese oxide based compounds. The colossal magnetoresistance figures obtained (about 80%) are determined by the fraction enlargement mechanism. Self-shielding of the memory to external fields is found under certain described circumstances. We show that this non-volatile memory has multilevel capability associated with different applied low magnetic field values.Acepted for publication in Phys. Rev. B: Rapid Comm. + corresponding author levy@cnea.gov.arThe unusually large change of resistivity following application of magnetic field, the so called colossal magnetoresistance (MR) effect observed in manganese-oxidebased compounds, is again being the focus of intense research due to the capability of small external forces to tailor the macroscopic materials response. This unique possibility is related to the simultaneous presence of submicrometer ferromagnetic metallic (FM) regions and charge ordered (CO) and/or paramagnetic insulating (PI)ones in some manganites, the Phase Separation (PS) phenomena.[1]The PS scenario fully develops in the La 5/8−y Pr y Ca 3/8 MnO 3 (LPCM(y)) family of compounds, whose end members exhibit homogeneous FM (y=0) and CO (y=1) states.[2] Intense research activities in these compounds were developed by Moscow groups [3][4][5] and by Cheongś group. [6][7][8][9][10][11][12] In short, these works show the tendency of LPCM(y) to form inhomogeneous structures, which seems to be a generic property of strongly correlated systems. [2,13] There are conclusive evidences, both theoretical [14,15]and experimental, [16,17] showing that the high values of MR achieved by PS manganites are due to the possibility of unbalancing the amount of the coexisting phases by the application of low magnetic fields. In La 0.5 Ca 0.5 MnO 3 , a prototypical PS compound with its charge ordering temperature T co lower than that of FM ordering T C , the huge values of the low field low temperature MR are related to the capability of the field to inhibit the formation of otherwise CO regions, leading to an effective increase of the FM fraction.[16] Remarkably, it was also shown that this process is only achieved when field cooling (FC) the sample.[16] Application of low H once the relative fractions of the coexisting phases were established has the only effect of domain alignment. At low temperature, this kind of MR affects mainly the intergrain tunneling in polycrystalline samples, with maximum values of the low field MR around 30%. [18,19] The application of moderate magnetic fields in the FC mode plays also an unbalancin...

show abstract

“…We note that these studies of grain size reduction in polycrystalline LPCMO have not crossed the ~100nm threshold, below which surface effects dominate the physics of manganite nanoparticles. 43 With the exception of our previous study on a closely related composition, 10 we find that despite wealth of available literature on thin films, [29][30][31][32][33][34][35][36][37]41 single- 19,22,25,26,28,40 and polycrystalline 8,9,14,17,18,20,21,23,24,45 forms of LPCMO, virtually no work has been done on nanoparticles of the same compounds, although reduction of particle size to well below the characteristic phase separation length can be expected to have a great impact on strain, and consequently on the magnetic properties of the system. 10 Adding an additional layer of interest, opposing surface-driven trends are observed in nanosized FM and CO compounds.…”

Section: Introductionmentioning

confidence: 78%

Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8−yPryCa
Bingham
¹
,
Lampen
²
,
Phan
³

et al. 2012
Phys. Rev. B

View full text Add to dashboard Cite

Bulk manganites of the form La 5/8-y Pr y Ca 3/8 MnO 3 (LPCMO) exhibit a complex phase diagram due to coexisting charge-ordered antiferromagnetic (CO/AFM), charge disordered paramagnetic (PM), and ferromagnetic (FM) phases. Because phase separation in LPCMO occurs on the microscale, reducing particle size to below this characteristic length is expected to have a strong impact on the magnetic properties of the system. Though a comparative study of the magnetic and magnetocaloric properties of single crystalline (bulk) and nanocrystalline LPCMO (y = 3/8) we show that the AFM, CO, and FM transitions seen in the single crystal can also be observed in the large particle sizes (400 nm and 150 nm), while only a single PM to FM transition is found for the small particles (55 nm). Magnetic and magnetocaloric measurements reveal that decreasing particle size affects the balance of competing phases in LPCMO and narrows the range of fields over which PM, FM, and CO phases coexist. The FM volume fraction increases with size reduction, until CO is suppressed below some critical size, ~100 nm. With size reduction, the saturation magnetization and field sensitivity first increase as long-range CO is inhibited, then decrease as surface effects become increasingly important. The trend that the FM phase is stabilized on the nanoscale is contrasted with the stabilization of the charge-disordered PM phase occurring on the microscale, demonstrating that 2 in terms of the characteristic phase separation length, a few microns and several hundred nanometers represent very different regimes in LPCMO. PACS: 75.30.Vn

show abstract

Multiphase segregation and metal-insulator transition in single crystalLa5/8−yPry

Cited by 73 publications

References 28 publications

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

Nonvolatile magnetoresistive memory in phase separatedLa0.325Pr0.300Ca

Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8−yPryCa
Bingham
¹
,
Lampen
²
,
Phan
³

et al. 2012
Phys. Rev. B

Contact Info

Product

Resources

About

Multiphase segregation and metal-insulator transition in single crystalLa5/8−yPry

Cited by 73 publications

References 28 publications

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

Tunneling study of the charge-ordering gap on the surface ofLa0.350Pr0.275Ca0.375MnO3

Nonvolatile magnetoresistive memory in phase separatedLa0.325Pr0.300Ca

Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8−yPryCaBingham1, Lampen2, Phan3 et al. 2012Phys. Rev. B

Contact Info

Product

Resources

About

Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8−yPryCa
Bingham
¹
,
Lampen
²
,
Phan
³

et al. 2012
Phys. Rev. B