Neutron scattering studies on stripe phases in non-cuprate materials

TL;DR

This paper reviews neutron scattering evidence of stripe phases in non-cuprate layered transition-metal oxides, highlighting their similarities and differences with cuprates, and emphasizing the role of charge, spin, and orbital degrees of freedom.

Contribution

It provides a comprehensive overview of stripe ordering phenomena in non-cuprate materials, emphasizing the influence of doping, charge mobility, and orbital effects on stripe formation.

Findings

Stripe order is common in non-cuprates upon doping.

Charge mobility influences the amount of doping needed for stripe phases.

Magnetic excitations in stripe phases resemble those in cuprates.

Abstract

Several non-cuprates layered transition-metal oxides exhibit clear evidence for stripe ordering of charges and magnetic moments. Therefore, stripe order should be considered as the typical consequence of doping a Mott insulator, but only in cuprates stripe order or fluctuating stripes coexist with metallic properties. A linear relationship between the charge concentration and the incommensurate structural and magnetic modulations can be considered as the finger print of stripe ordering with localized degrees of freedom. In nickelates and in cobaltates with K2NiF4 structure, doping suppresses the nearest-neighbor antiferromagnetism and induces stripe order. The higher amount of doping needed to induce stripe phases in these non-cuprates series can be attributed to reduced charge mobility. Also manganites exhibit clear evidence for stripe phases with further enhanced complexity, because orbital degrees of freedom are involved. Orbital ordering is the key element of stripe order in manganites since it is associated with the strongest structural distortion and with the perfectly fulfilled relation between doping and incommensurability. Magnetic excitations in insulating stripe phases exhibit strong similarity with those in the cuprates, but only for sufficiently short magnetic correlation lengths reflecting well-defined magnetic stripes that are only loosely coupled.