Experimental confirmation of Zener-polaron-type charge and orbital ordering in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>Pr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ca</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>MnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Wu, Lijun; Klie, Robert F.; Zhu, Yimei; Jooß, Ch.

doi:10.1103/physrevb.76.174210

Cited by 84 publications

(80 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Experiments provide structural evidence for Zener polarons. [36,37] They are further supported by the observation, that in the charge-ordered state of PCMO in a doping range of 0.3 ≤ x ≤ 0.5, the spatial variation of charge carrier density occurs on oxygen sites, [8] whereas the valence separation between different Mn sites is rather low. [8,[38][39][40] Since the Mn 3d e g states have the same parity with respect to the Mn-site, the optical transition between JT split states, such as the one from orbital α 1 to β 1 in Figure 7, is dipole forbidden.…”

Section: Jahn-teller Dimer Modelsupporting

confidence: 61%

Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Raiser

Mildner

Ifland

et al. 2017

Advanced Energy Materials

View full text Add to dashboard Cite

Understanding and controlling the relaxation process of optically excited charge carriers in solids with strong correlations is of great interest in the quest for new strategies to exploit solar energy. Usually, optically excited electrons in a solid thermalize rapidly on a femtosecond to picosecond timescale due to interactions with other electrons and phonons. New mechanisms to slow down thermalization will thus be of great significance for efficient light energy conversion, e.g., in photovoltaic devices. Ultrafast optical pump–probe experiments in the manganite Pr0.65Ca0.35MnO3, a photovoltaic, thermoelectric, and electrocatalytic material with strong polaronic correlations, reveal an ultraslow recombination dynamics on a nanosecond‐time scale. The nature of long living excitations is further elucidated by photovoltaic measurements, showing the presence of photodiffusion of excited electron–hole polaron pairs. Theoretical considerations suggest that the excited charge carriers are trapped in a hot polaron state. Escape from this state is possible via a slow dipole‐forbidden recombination process or via rare thermal fluctuations toward a conical intersection followed by a radiation‐less decay. The strong correlation between the excited polaron and the octahedral dynamics of its environment appears to be substantial for stabilizing the hot polaron.

show abstract

Section: Jahn-teller Dimer Modelsupporting

confidence: 61%

Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Raiser

Mildner

Ifland

et al. 2017

Advanced Energy Materials

View full text Add to dashboard Cite

show abstract

“…The more distorted the system is, the more effective the Coulomb and JT interactions are in stabilizing the ZP phase. Despite initial controversies 12,13 the presence of ZP ordering in Pr 1−x Ca x MnO 3 is now conclusively established [1][2][3] . From the experimental point of view it has been difficult to establish directly the existence of ferroelectricity in charge ordered manganites due to the finite conductivity and the associated problem of leakage.…”

Section: Introductionmentioning

confidence: 99%

“…Several theoretical models have been put forward: first, the static long-range ordering of bond-centered (BC) 'Zener polarons' (ZP) 1 whereby one e g electron is shared by two equivalent Mn 3.5+ ions and the accompanying dimerisation results in the noncentrosymmetric P2 1 nm space group leading to spontaneous axial electric polarization 2,3 ; second, the coexistence of classic checkerboard type 'site-centered' (SC) charge ordering and ZP/BC ordering could lead to the breaking of inversion symmetry causing axial as well as non-axial polarization [4][5][6] ; third, finite dislocation in a spin density wave, commensurate with respect to the lattice, can give rise to ferroelectric instability without breaking the inversion symmetry in the magnetic structure 7 ; fourth, strong electron-electron interactions combined with the Jahn-Teller (JT) lattice distortions can cause a canting instability of its antiferromagnetic (AFM) ground state and the resulting non-collinear magnetic ordering induces ferroelectricity of purely electronic origin 8 .…”

Section: Introductionmentioning

confidence: 99%

Direct experimental evidence of multiferroicity in a nanocrystalline Zener polaron ordered manganite

et al. 2014

View full text Add to dashboard Cite

We discuss the particle size driven tunability of the coexistence of ferromagnetism and ferroelectricity in Pr0.67Ca0.33MnO3 (PCMO) with the help of x-ray diffraction (XRD), magnetization, impedance spectroscopy and remanent polarization measurements. The remanent polarization measurements using 'Positive Up Negative Down' (PUND) method clearly prove the existence of ferroelectricity in PCMO with phase separation between Zener Polaron (ZP) ordered P21nm and disordered Pbnm structures. We also find that the ferroelectric response is enhanced in nanocrystalline samples so long as ZP ordering is not destroyed while the long range antiferromagnetic ordering at low temperature in bulk system is replaced by ferromagnetic correlations in nanoparticles. The conclusion, that by reducing the crystallite size, it might be possible to make ferromagnetism and ferroelectricity coexist near room temperature, should be generally applicable to all ZP ordered manganites. [Published: Phys. Rev. B 90, 245126 (2014)]

show abstract

“…[23][24][25][26][27][28][29][30][31][32][33][34][35] Fig. 4(a) is a [001] HRTEM image of the CO1 phase.…”

mentioning

confidence: 99%

Microstructure of bilayer manganite PrCa2Mn2O7 showing charge/orbital ordering

Tian

Deng

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

The microstructure of the charge/orbital ordering Ruddleden-Popper phase PrCa 2 Mn 2 O 7 was studied by transmission electron microscopy along both the [001] and the [110] orientation. Three coexisting charge/orbital ordering phases CO1, CO2, and CO3 were observed along the [001] orientation at room temperature. Different from the one-dimensional modulation in the CO1 and CO2 phase, the CO3 phase is characterized by two sets of mutually perpendicular structural modulations. From [110] high angle annular dark field-scanning transmission electron microscopy, we found that the Pr atoms locate in-between the bilayer MnO 6 octahedra, which is different from the previous reports. The strongly correlated electronic systems of perovskite manganites have received great attention because of their fascinating physical properties such as colossal magnetoresistance and high spin polarity, which could find potential applications in spintronics or magnetic tunnel junction. [1][2][3][4][5][6][7][8][9] The physical mechanism of these properties was ascribed to the complicated interplays between the four degrees of freedom of lattice, charge, orbital, and spin, and the consequent ordering as well as possible phase separation. 6,[10][11][12] Recently, two distinct charge/orbital ordering (CO/OO) states were found in the Ruddlesden-Popper (RP) compound Pr(Sr 1Àx Ca x ) 2 Mn 2 O 7 . 13 Pr(Sr 1Àx Ca x ) 2 Mn 2 O 7 has a layer structure (AO) (ABO 3 ) n (n ¼ 2), where two (ABO 3 ) perovskite layers are separated by a AO rock salt layer along the long axis. The two reported CO/OO phases in Pr(Sr 0.1 Ca 0.9 ) 2 Mn 2 O 7 are the high-temperature phase CO1 phase at 330 K > T > 295 K (lattice parameters a ¼ 0.5412, b ¼ 1.0921, c ¼ 1.9234 nm, and space group Pbnm) and the lower-temperature CO2 phase at T < 295 K (a ¼ 1.0812, b ¼ 0.5475, c ¼ 1.9203 nm, and space group Am2m, Ref. 13). The CO1 phase is centrosymmetric without any spontaneous electric polarization, but the CO2 phase is a noncentrosymmetric phase with spontaneous electric polarization. 13 The thermally induced rotation of orbital stripes between these two ordering phases has attracted extensive interest. [14][15][16][17][18] However, the limited information about its microstructures has obstructed a better understanding of the macro properties and physics underneath. Therefore, we carried out a transmission electron microscopy (TEM) study on PrCa 2 Mn 2 O 7 to reveal the different aspects of the microstructure. The phases and micro domains viewed along the [001] zone axis are discussed. The heavy Pr atoms were found to locate inbetween the bilayer MnO 6 octahedra.Bulk PrCa 2 Mn 2 O 7 samples were synthesized using a traveling solvent floating zone method with high oxygen background pressure. 17,18 Powdered samples, deposited on a Cu grid coated with a holey carbon film, as well as Ar-ion milled TEM samples were used for TEM investigation. A Tecnai G 2 electron microscope equipped with a Gatan cooling and heating holder operated at 200 kV was used to record electron diffractio...

show abstract

Experimental confirmation of Zener-polaron-type charge and orbital ordering inPr1−xCaxMnO3

Cited by 84 publications

References 53 publications

Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Evolution of Hot Polaron States with a Nanosecond Lifetime in a Manganite Perovskite

Direct experimental evidence of multiferroicity in a nanocrystalline Zener polaron ordered manganite

Microstructure of bilayer manganite PrCa2Mn2O7 showing charge/orbital ordering

Contact Info

Product

Resources

About