angular material design ui router not working

i am implementing angular material design with horizontal md-tab there are no any errors but still content of tabs are blank.thank you in advance.

index.html

    <!DOCTYPE html>
<html>
<head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <meta name="apple-mobile-web-app-capable" content="yes">
        <meta name="apple-mobile-web-app-status-bar-style" content="black">

    <link rel="stylesheet" href="angular-material/angular-material.css">
    <style >
 .mainApp md-content .ext-content {
  padding: 50px;
  margin: 20px;
  background-color: #FFF2E0; }
  </style>
</head>
<body ng-app="mainApp">
    <div ng-controller="AppCtrl" layout="column" ng-cloak>
    <div id="logo" >
    <script type="text/ng-template" id="views/home.html" ></script>
  <script type="text/ng-template" id="views/aboutus.html"></script>
  <script type="text/ng-template" id="views/services.html"></script>
  <script type="text/ng-template" id="views/contactus.html"></script>

   <md-tabs md-stretch-tabs="always" class="md-primary" md-selected="selectedIndex">

    <md-tab data-ui-sref="home" md-active="state.is('home') ">
    <md-tab-label>HOME</md-tab-label>
    </md-tab>

    <md-tab data-ui-sref="aboutus" md-active="state.is('aboutus')">
    <md-tab-label>ABOUT US</md-tab-label>
    </md-tab>

    <md-tab data-ui-sref="services" md-active="state.is('services')">
    <md-tab-label>SERVICES</md-tab-label>
    </md-tab>

    <md-tab data-ui-sref="contactus" md-active="state.is('contactus')">
    <md-tab-label>CONTACT US</md-tab-label>
    </md-tab>
<!--     <md-tab id="tab1" label="HOME" aria-controls="tab1-content" md-nav-click="goto('home')"></md-tab>
    <md-tab id="tab2" label="ABOUT US" aria-controls="tab2-content" md-nav-click="goto('aboutus)"></md-tab>
    <md-tab id="tab3" label="SERVICES" aria-controls="tab3-content" md-nav-click="goto('services')"></md-tab>
    <md-tab id="tab4" label="CONTACT US" aria-controls="tab4-content" md-nav-click="goto('contactus')"></md-tab>
 -->  </md-tabs> 

  <div id="content" ui-view flex> </div>

    </div>

    <script src="angular/angular.js"></script> 
    <script src="angular-material/angular-material.js"></script> 
    <script src="angular-aria/angular-aria.js"></script> 
    <script src="angular-animate/angular-animate.js"></script> 
    <script src="angular/angular-ui-router.min.js"></script>
    <script src="controller/controller.js"></script> 

</body>
</html>

     controller.js

(function(angular, undefined) {
    "use strict";
    angular.module('mainApp', ['ngMaterial',  "ui.router"])
    .config(function($stateProvider, $urlRouterProvider) {

        $urlRouterProvider.otherwise('/home');
        $stateProvider
        .state('home', {
            url: "/home",
            templateUrl: "views/home.html"
        })
        .state('aboutus', {
            url: "/aboutus",
            templateUrl: "views/aboutus.html"
        })
        .state('services', {
            url: "/services",
            templateUrl: "views/services.html"
        })
        .state('contactus', {
            url: "/contactus",
            templateUrl: "views/contactus.html"
        })
        ;
    })
    .controller('AppCtrl', function($scope,$state, $location, $log) {
        $scope.selectedIndex = 0;
        $scope.$watch('selectedIndex', function(current, old) {
            switch (current) {
                case 0:
                    $location.url("/home");
                    break;
                case 1:
                    $location.url("/aboutus");
                    break;
                case 2:
                    $location.url("/services");
                    break;
                case 3:
                    $location.url("/contactus");
                    break;
            }
        });
    });

})(angular);

aboutus.html

<div flex layout="row">
     <h1>The super duper awesome Contact Form will go here!</h1>
</div>

same code for contact and services.html

I created the same application, probably you are missing some references that matches angular-material,

 <link rel="stylesheet" href="//rawgit.com/angular/bower-material/master/angular-material.css" />
 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.3.15/angular.js"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.3.15/angular-animate.js"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.3.15/angular-aria.js"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular-ui-router/0.2.14/angular-ui-router.js"></script>
 <script src="//rawgit.com/angular/bower-material/master/angular-material.js"></script>

Here is the Working App