Twisted artificial crystal opens up new possibilities for storing information

An international study led by the Complutense University of Madrid (UCM) has succeeded in assembling monocrystalline layers of Ceramic oxides Just a few atoms thick, rotated at any angle, they combine to form a new artificial crystal that does not exist in nature.

The work, published in Natureshows that at the interface between twisted ferroelectric layers one of these ceramic oxides Barium titanate (BaTiO3), new properties are emerging that could bring about a revolution in materials science and technology. The BaTiO3 It has been known since the beginning of the last century and, like graphene, is produced in the form of ultra-thin crystals.

This new generation of artificial materials is created by stacking two ultra-thin crystals of a ceramic oxide, barium titanate, which are rotated relative to each other.

In nature, crystals grow spontaneously with well-defined facets as they maintain the orientation of the so-called crystals Crystal axesSizes of several tens of meters and weights of several tons can be achieved.

To date, modern material growth technologies exploit this natural tendency by combining very thin layers of different materials that are stacked on top of each other, while strictly maintaining the crystal orientation and the arrangement of the atoms of the different layers. The result is the appearance of something new and interesting Properties at interfaces or connecting surfaces between the crystalline layers, which have enabled, for example, the construction of electronic devices and their use in information and communication technology.

The “Twistronics” and the pattern moire

In this work, oxide crystals were created with a new degree of freedom that does not exist in nature and has not been possible to date: the controlled rotation between crystalline layers of atomic thickness, a strategy that we describe in a misuse of language “Twistronics” (in English, Twistronics, the study of how the angle or rotation between layers of two-dimensional materials can change their electrical properties).

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The connection of these layers creates a characteristic structure and interaction pattern (so-called Pattern moire), which, according to theoretical calculations by Hugo Aramberri and Jorge Iñiguez at the Luxembourg Institute of Science and Technology (LIST, in Luxembourg), is the origin of the emergent properties found.

The work shows that rotation between layers induces a never-before-seen ferroelectric state in which they alternate electrically polarized vortices (vortices) with a very small lateral size (a few atoms) and the information element (bits) of it could be memories of the Future.

The work opens new ways to increase the information storage density and energy efficiency of future computing devices

Jacobo SantamariaDirector of the “Physics of Complex Materials” group at the UCM explains that storage densities could be achieved in this state would exceed 100 terabits/inch2 Exceeding the current limit of 1 TB/inch2 in which the information density of computer memories has stagnated for several years.

This would enable us to address the technological and energy sustainability challenge of global information storage, which could go beyond Yotta (1024) bytes in the current decade. According to the authors, this work opens new avenues for increasing the information storage density and energy efficiency of future computing devices.

Carlos Leonadds a researcher from the same group: “Furthermore, this study opens a whole range of possibilities for the observation and exploitation of new effects and properties in other crystalline oxides (and not only oxides) that exhibit ferroic or multiferroic states or other collective states.” ” .

In addition to the UCM and the LIST, the Institute of Materials Sciences of Madrid (CSIC) and the Laboratory of Heterostructures with Applications in Spintronics, also from the UCM and the CSIC, also participated in this research.


G. Sánchez-Santolino, J. Santamaria et al. “A 2D ferroelectric vortex pattern in twisted free-standing BaTiO3 layers”. Nature

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