Ultrahigh Kinetic Inductance Superconducting Materials from Spinodal Decomposition

Abstract

Disordered superconducting nitrides with kinetic inductance have long been considered to be leading material candidates for high‐inductance quantum‐circuit applications. Despite continuing efforts toward reducing material dimensions to increase the kinetic inductance and the corresponding circuit impedance, achieving further improvements without compromising material quality has become a fundamental challenge. To this end, a method to drastically increase the kinetic inductance of superconducting materials via spinodal decomposition while maintaining a low microwave loss is proposed. Epitaxial Ti0.48Al0.52N is used as a model system and the utilization of spinodal decomposition to trigger the insulator‐to‐superconductor transition with a drastically enhanced material disorder is demonstrated. The measured kinetic inductance increases by two to three orders of magnitude compared with the best disordered superconducting nitrides reported to date. This work paves the way for substantially enhancing and deterministically controlling the inductance for advanced superconducting quantum circuits.

Stabilizing Supersaturation with Extreme Grain Refinement in Spinodal Aluminum Alloys

“…[2,[15][16][17] The spontaneous decomposition of the supersaturated phase starts from small composition fluctuation through local "uphill" diffusion without an energy barrier to nucleation, forming compositional modulations composed of two conjugate phases with the same lattice symmetry but different compositions until the eventual development of interface at the late stage. [18][19][20] In fact, spinodal decomposition takes place in the very initial stage of many precipitation processes and eutectoid transformations, such as the formation of G.P. zones in Al or Cu alloys and of cementite in steels.…”

Defects in Titanium Aluminum Nitride-Based Thin Films

“…Ti-Al-Nbased films are versatile and offer a range of benefits for a variety of applications. Films in this system have found applications as protective [1,4], electronic [15], optical [16], plasmonic [17], and recently, as superconducting [18] films. Within the Ti-Al-N system, a large variety of stable binary and ternary phases exists.…”

“…As mentioned in the introduction, the interest to understand the decomposition of Ti1-xAlxNy is because of its role in age hardening of coatings [5]. Besides age hardening, however, the spinodal decomposition process of c-Ti-Al-N has recently garnered attention as a model system to tune the insulator-to-superconductor transition in films through enhanced material disorder [18]. A calculated quasi-binary phase diagram for Ti1-xAlxN is shown in Figure 2.3, which shows the existence of a miscibility gap for a wide range of x values [37].…”

High-resolution STEM investigation of the role of dislocations during decomposition of Ti1-xAlxNy

“…Growing solid solution coatings with compositions within the spinodal region that harden during service is a common strategy for protecting metal cutting tools [3,4]. TiAlN, the archetypal material system for this phenomenon, has been proven to be a suitable coating not just for cutting tools [5], but also has applications as microelectronic [6], optoelectronic [7], and superconductive films [8]. The spinodal decomposition of TiAlN occurs by an isostructural segregation of the rocksalt face-centered cubic (FCC or c-) solid solution into coherent c-TiN-rich and c-AlN-rich domains [9,10].…”