Rice University researchers have found a way to isolate a single magnetic domain in manganese telluride, giving them a clearer view of its magnetic structure and a new way to control an electrical effect in the material.<\/p>\n
The work focuses on altermagnetism, a recently recognized form of magnetism that could offer a different route to spin-based electronics. Researchers are interested in altermagnets because they may combine useful properties of ferromagnets and antiferromagnets while potentially enabling faster, lower-heat information processing.<\/p>\n
The challenge is that manganese telluride normally forms multiple magnetic domains, which can point in different directions. Their signals can overlap, making it difficult to determine the material\u2019s intrinsic magnetic structure.<\/p>\n
The Rice team addressed the problem by applying uniaxial strain, stretching the manganese telluride in one direction. This forced the material into a single-domain state that could be measured more clearly.<\/p>\n
Stretching reveals hidden magnetism<\/p>\n
\u201cAltermagnets like hexagonal manganese telluride typically form multidomain structures where the magnetic forces divide into separate equivalent domains that spin in different directions to satisfy the underlying threefold rotational symmetry of the hexagonal lattice,\u201d said Dai, the Sam and Helen Worden Professor of Physics and Astronomy. <\/p>\n
\u201cThe signals from these coexisting domains could overlap, making it hard to know what the underlying magnetic structure actually is. Here, we were able to apply a uniaxial strain, which resulted in a single magnetic domain we could clearly resolve into the underlying magnetic structure.\u201d<\/p>\n
The single-domain state also allowed the researchers to observe a sharp feature in the material\u2019s anomalous Hall effect, which produces a voltage across a material when electrical current flows through it and is influenced by its magnetic properties.<\/p>\n
At about 230 kelvin, or minus 45 degrees Fahrenheit, the researchers found that strain could change the polarity of this Hall signal. The electrical response could therefore be switched without substantially changing the material\u2019s underlying magnetic interactions.<\/p>\n
\u201cBy applying the uniaxial strain, we were able to finally resolve the magnetic structure of manganese telluride,\u201d said Sijie Xu, a Rice graduate student and co-first author. \u201cThis also allowed us to see a remarkably sharp feature in the anomalous Hall signal, which describes a lateral voltage generated when an electrical current flows through the material due to its magnetic structure.\u201d<\/p>\n
Strain offers temperature alternative<\/p>\n
The researchers believe the tunability comes from changes in the material\u2019s Berry curvature, a property that describes how electrons behave as they move through a material\u2019s electronic<\/a> structure.<\/p>\n The scale of the required strain is also significant. The team\u2019s calculations suggest that a 1% change in strain could produce an effect equivalent to changing the temperature by about 150 kelvin.<\/p>\n