An itinerant antiferromagnetic metal without magnetic constituents

Abstract

The origin of magnetism in metals has been traditionally discussed in two diametrically opposite limits: itinerant and local moments. Surprisingly, there are very few known examples of materials that are close to the itinerant limit, and their properties are not universally understood. In the case of the two such examples discovered several decades ago, the itinerant ferromagnets ZrZn2 and Sc3In, the understanding of their magnetic ground states draws on the existence of 3d electrons subject to strong spin fluctuations. Similarly, in Cr, an elemental itinerant antiferromagnet with a spin density wave ground state, its 3d electron character has been deemed crucial to it being magnetic. Here, we report evidence for an itinerant antiferromagnetic metal with no magnetic constituents: TiAu. Antiferromagnetic order occurs below a Néel temperature of 36 K, about an order of magnitude smaller than in Cr, rendering the spin fluctuations in TiAu more important at low temperatures. This itinerant antiferromagnet challenges the currently limited understanding of weak itinerant antiferromagnetism, while providing insights into the effects of spin fluctuations in itinerant–electron systems.

Competing magnetic instabilities in the weak itinerant antiferromagnetic TiAu

“…2. The DOS was presented earlier by Svanidze et al 9 and is consistent with our result (which we have converged more highly due to the extreme fine structure). The bands along symmetry lines seem conventional for a metal, with several Fermi level (E F ) crossings.…”

“…II, of the electronic structure and magnetic tendencies of TiAu, with the goal of illuminating behavior associated with its weak itinerant antiferromagnetism. Svanidze et al 9 provided several characteristics of the electronic structure and magnetic energies of TiAu. In Sec.…”

Antiferromagnetic spintronics

“…These alloys offer the possibility to exploit rare-earth-based antiferromagnetic metals. Other materials may also be interesting to consider for future fundamental studies on antiferromagnetic spintronics, such as TiAu (Svanidze et al, 2015), an itinerant antiferromagnet without magnetic constituents, or CrB 2 (Brasse et al, 2013) which potentially combines antiferromagnetic spintronics and superconductivity.…”

Quantum critical point in the Sc-doped itinerant antiferromagnet TiAu

“…The latter question has numerous ramifications, considering the complexity of the phenomena accompanying QCPs in both dand f -electron systems: unconventional superconductivity (SC) [1][2][3][4], non-Fermi liquid (NFL) [5][6][7][8] and heavy fermion (HF) behavior [7,[9][10][11][12]. In this paper we report a QCP in the first itinerant antiferomagnetic metal (IAFM) without magnetic constituents, TiAu [13]. By comparison with the only two other itinerant magnets with no magnetic elements, ZrZn 2 [14] and Sc 3.1 In [15], both ferromagnets, we will articulate the differences and similarities stemming from the two kinds of magnetic order.…”

“…The d-electron (transition metal) systems showing quantum criticality are noticeably fewer than the felectron (rare earth) ones, with remarkably few (only three) transition metal itinerant magnets (IMs) with no magnetic elements: the itinerant ferromagnets (IFMs) ZrZn 2 [14], Sc 3.1 In [15], and the itinerant antiferromagnet (IAFM) TiAu [13]. Surprising similarities and substantive differences exist between the FM and AFM ordered states, in both local and itinerant moment systems: (i) pressure [16] and doping [17] both suppress the FM order in ZrZn 2 , but have opposite effects in the IFM Sc 3.1 In [18,19]; (ii) NFL behavior accompanies the QCP in the doped FMs, the d-electron Sc 3.1 In [19] and f -electron HF URu 2 Si 2 [20], with non-mean-field scaling in both compounds contrasting the mean-field and Fermi liquid (FL) behavior in the IFM ZrZn 2 [17]; (iii) modest pres- * Currently at Max Planck Institute for Chemical Physics sure increases the magnetic ordering temperature in both the IAFM TiAu [21] and the IFM Sc 3.1 In [18].…”