10 fs Dynamics of Photoinduced Magnetic Transition in Double-Layered Charge Ordering in LuFe2O4 Under Interlayer Excitation

The largest single crystals of potassium birnessite thus far reported are grown. The structure is studied at atomic resolution. Mn3+/Mn4+ charge ordering, structural modulation and stacking faults are found.

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Imaging the formation and surface phase separation of the CE phase

npj Quantum Materials ◽

10.1038/s41535-021-00353-2 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Haibiao Zhou ◽

Qiyuan Feng ◽

Yubin Hou ◽

Masao Nakamura ◽

Yoshinori Tokura ◽

...

Keyword(s):

Magnetic Field ◽

Phase Transitions ◽

Charge Ordering ◽

Zero Magnetic Field ◽

Ferromagnetic Phase ◽

Emergent Properties ◽

Orbital Ordering ◽

Strong Electron ◽

Antiferromagnetic Correlation ◽

Ordering Transitions

AbstractThe CE phase is an extraordinary phase exhibiting the simultaneous spin, charge, and orbital ordering due to strong electron correlation. It is an ideal platform to investigate the role of the multiple orderings in the phase transitions and discover emergent properties. Here, we use a cryogenic high-field magnetic force microscope to image the phase transitions and properties of the CE phase in a Pr0.5Ca0.5MnO3 thin film. In a high magnetic field, we observed a clear suppression of magnetic susceptibility at the charge-ordering insulator transition temperature (TCOI), whereas, at the Néel temperature (TN), no significant change is observed. This observation favors the scenario of strong antiferromagnetic correlation developed below TCOI but raises questions about the Zener polaron paramagnetic phase picture. Besides, we discoverd a phase-separated surface state in the CE phase regime. Ferromagnetic phase domains residing at the surface already exist in zero magnetic field and show ultra-high magnetic anisotropy. Our results provide microscopic insights into the unconventional spin- and charge-ordering transitions and revealed essential attributes of the CE phase, highlighting unusual behaviors when multiple electronic orderings are involved.

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Complex magnetic properties associated with competing local and itinerant magnetism in $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$

Scientific Reports ◽

10.1038/s41598-021-90751-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mily Kundu ◽

Santanu Pakhira ◽

Renu Choudhary ◽

Durga Paudyal ◽

N. Lakshminarasimhan ◽

...

Keyword(s):

Heat Capacity ◽

Neutron Diffraction ◽

Single Phase ◽

Magnetic Transition ◽

Muon Spin Rotation ◽

Antiferromagnetic Coupling ◽

Diffraction Measurement ◽

Zero Field ◽

Crystalline Electric Field ◽

X Ray

AbstractTernary intermetallic compound $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$ Pr 2 Co 0.86 Si 2.88 has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ($$\mu$$ μ SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below $$\sim$$ ∼ 4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field $$\mu$$ μ SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below $$\sim$$ ∼ 20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

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