Hidden k-Space Magnetoelectric Multipoles in Nonmagnetic Ferroelectrics

Area of Science:

• Condensed matter physics
• Materials science
• Quantum mechanics

Background:

• Electronic degrees of freedom in condensed matter can form complex composites called hidden orders, leading to unusual properties not detectable by conventional experiments.
• Broken space-inversion symmetry in nonmagnetic materials can lead to novel electronic phenomena.
• Ferroelectric materials, like PbTiO3, exhibit broken inversion symmetry and ferroelectric polarization.

Purpose of the Study:

• To demonstrate the existence of hidden k-space magnetoelectric multipoles in nonmagnetic systems with broken space-inversion symmetry.
• To establish a link between these k-space multipoles and real-space charge dipoles.
• To propose an experimental method for detecting and tuning these hidden multipoles.

Main Methods:

• Theoretical investigation of electronic structures in systems with broken space-inversion symmetry.
• Utilizing PbTiO3 as a prototypical ferroelectric material.
• Proposing the use of magnetic Compton scattering to detect k-space magnetoelectric toroidal moments.

Main Results:

• Demonstrated the existence of hidden k-space magnetoelectric multipoles in nonmagnetic systems with broken space-inversion symmetry.
• Identified the origin of these multipoles as spin asymmetry in momentum space due to broken inversion symmetry.
• Showed that these multipoles manifest as a k-space magnetoelectric toroidal moment in PbTiO3.
• Established that this toroidal moment can be detected by magnetic Compton scattering and reversed by an electric field.

Conclusions:

• Hidden k-space magnetoelectric multipoles are a fundamental property of nonmagnetic materials with broken space-inversion symmetry.
• Magnetic Compton scattering offers a novel experimental route to probe these hidden multipoles in nonmagnetic systems.
• Electric field control of these multipoles opens possibilities for novel electronic devices and functionalities.