Field activated solid-state thermal switches and sub-kelvin adr stage including field activated solid-state thermal switches

A thermal switch, comprising:

• a magnetothermal element including a first end face and a second end face, the magnetothermal element being made of a magnetothermal material that is a member of a group consisting of trivial semimetals, Dirac semimetals, Weyl semimetals when a magnetic field is applied to a direction normal to a separation of Weyl points in the magnetothermal material, Weyl semimetals when the magnetic field does not have a component parallel to the separation of Weyl points and normal directions to at least one of the first end face or the second end face of the magnetothermal material, and intrinsic semiconductors and topological insulators when the magnetic field does not induce Weyl semimetal phase with an energy gap less than kBT where T is an operating temperature;
• a first thermal terminal thermally coupled to the first end face of the magnetothermal element;
• and
• a second thermal terminal thermally coupled to the second end face of the magnetothermal element.

A method of controlling heat flow, comprising:

• providing a magnetothermal element including a first end face and a second end face, the magnetothermal element being made of a magnetothermal material that is inherently or is inducible by a magnetic field into being a Weyl semimetal;
• thermally coupling a first thermal terminal to the first end face of the magnetothermal element;
• and
• thermally coupling a second thermal terminal to the second end face of the magnetothermal element.